dabzeil, loosen the chain so you can remove it from the small sprocket on top of the motor unit. This is a good time to take a good look at that sprocket. It should be level. This is usually the reason the chain comes off. Now run the opener until that sprocket turns counterclockwise and stops. This is the door open position for the opener. Now with the door in the open position reinstall the chain. Do not over tighten the chain it shouldn't be stiff tight. You will now need to adjust the limit switches. If you don't find out why the chain came off you will be doing this all over again.

I had sort of the same issue. My Craftsman 139.53644SRT's gear went bad, so I had my dad replace it for me. BUT, after he replaced it, the door would have issues closing as it would almost snap the rail and when it came up it would only go 3 inches and stop, like it didn't know where to stop although we didn't touch any adjustments. Driving me nuts. He forgot to run the opener and let it take a full run clockwise before re-attaching the chain. Could this have been my problem? Should I unhook the door, take the chain off and let it run till it stops, and then with the door open reconnect the chain and tighten accordingly? Sorry for bad spelling, I've been trying to figure this out for a while and I'm dead tired. Any help is greatly appreciatd.

Hi Ryan, yes you are probably on the right path to repair. The trolley that moves on the bar has two parts, Inner and outer. When the door is closed, the outer trolly will be down by the front of the bar. When the limit switch is agianst the down limit the inner trolly (the one connected to the chain) should be right there inside the outer trolley. ALWAYS test this with the release handle pulled after any repair. If they dont line up then fix like you described above. I often do it by removing the limit assy and moving everything but your idea might be simpler for you to do. HTH Dave.

Thanks Dave --- I'll try that today when it warms up a bit. I think it will be easier once I remove the chain and the trolly doesn't go nuts and bend the rail up again. I'll let you guys know.

We took it off and the opener is doing the same thing withiout the chain on....it will try to go down for about 2 seconds then up about 2 seconds like it ignores the limitors. The SRT buttons is also flashing 4 times then quits...then repeats. I can't find this code anywhere -- any ideas?

I just got off the phone with tech support, and they said they think it's the board. I guess it'll be worth a shot to replace. If it doesn't work, then I'll take it back and just replace the darn thing.

ryank don't do anything rash yet. The LED flashing 4 times is the code for mis-aligned door sensors. Check to make sure they are still pointed directly at one another and the small light on each one is on. Try this and post back. We are really stubborn here on this forum and will help you.

I have an old chain driven garage door that the chain has come off of. Can someone help me figure out how to get the chain back on?

I inherited the opener with the house and have no idea where the manuals are. Thanks! Lyn

breezemom2 it is not normal for the chain to come off and usually is the indication of a bigger problem. The most common cause is worn bearings in the gear and sprocket assembly that lets that part lean towards the door and causes the chain to slip off the sprocket. You should not be able to move that part back and forth. If that is not the case you can loosen the chain at the trolley. (the part the door is connected to) Get on a step ladder and using your remote operate the opener until that sprocket on top of the motor unit turns clockwise and stops. You can now put the chain back on and tighten. Don't tighten too much. If you have problems post back and we will try to help.

hi 1/2 hp craftsmams GDO and im having problems on trying to get it to open. I tried to pick the door up by hand and it seem very heavy. I've lifted the door before and i could easily lift it with one hand but now i cant.

The GDO seems to go up 2-4 inchs then stops and goes back down and then makes several clicking noises. If i repeat this process i can get the door to go up halfway then it finally raises all the way up on its own, but i have encounter the same problem for it going down.

All infared sensors are green and dont really know what else to do. Could it be a bad spring and how do i check for that to see if it is? thanks for any input..

I have an Automatic Doorman Model 455 that came with my house when I moved in last year. Recently it stopped working. When I press the button from inside or the remote, I can hear a buzz sound that takes about 10 minutes to stop with a smell of a burning wire or rubber. Any suggestions?

Cam across this posting and was hoping someone could help -
The sprocket on my garage door opener is slightly raised and leaning more towards the door making the chain fall off. (5 years old) Is this something that can be replaced by ordering a new sprocket or something or once this happens it is not worth fixing ?

bbolf that is an easy repair. The part number is 41C4220A and is available from Sears or most any door opener service company.

I have a craftsman 1/2 garage door opener with keypad entry, remote and standard inside opener. I recently started having problems with not being able to use the keypad entry and the remote entry. Either one or the other only works not both. I have reset this thing I cant even count how many times. (even gotten stuck in the garage when even the button on the inside wouldnt work, but could hear the clicking of the unit). Read the book top to bottom and it offers no solution. Any one have any suggestions?

I have a craftsman 1/2hp model# 139.53641SRT. Two weeks ago the unit opened the garage door as usual and it hasn't worked since. When I push the wall pad or a remote the unit clicks like it wants to work but nothing happens. The light bulbs do not come on and the LED light blinks 5 times repeatedly. Is this a bad motor? Thanks

A few more notes. The motor does turn easily by hand, the motor starter capacitor is ok (swapped it with another unit) and the light bulbs do not operate, even when I unplug and replug the unit.

We have a Craftsman 1/2 hp Garage Door Opener, Chain Drive Model 53920. It was already installed on the home we purchased two years ago. Up until recently it was working with minor problems. Sometimes we would hear a clicking noise while it opens or closed, but I figured that was how it was suppose to sound since this was our first house and we never had a garage before. We have a wireless remote, a wireless car remote and a wall remote and none of them will open the garage. You can hear the motor running but the chain is not moving. I don't want to have to replace the entire unit, Can some one please help?

I have a Craftsman 53920 Garage Door opener and having no luck in programming my HomeLink in my Honda to operate it. Can someone please provide insights?

My garage door goes down and presses on the floor and then comes back up again. It will not stay down. Any thoughts?

On the side of the motor unit you will find the 'down limit control'. Turn this in the opposite direction of the arrow printed on the cover until you eliminate this problem but the door still closes.

don, thanks I will try this when i get home. on my wifes garage door i'm going to have to replace the gear and sprocket. the white tooth thing was not gripping anymore and was worn down. i had the white shavings all over when i took the cover off. i ordered the part yesterday, but i only hope i will be able to replce it. the guy on the phone said it was easy, but we'll see. i might be right back on here asking for advise.

All, I had to replace my gear, becasue it was stripped. When I was finished the door worked momentarily, but when it went all the way to the top, and I pressed the button for it to come down it just made a buzzing sound and didn't do anything. I saw that there was a small green light blinking at the back of the opener. Any ideas? Any help would be greatly appreciated.

y 1/2hp Craftsman garage door will not open.
-the door opens ok w/ the disengage handle pulled
-the motor grinds and the chain does not move with or w/o my help
-No lights flashing at end of cycle
-Motor runs about 15 sec then stops
-Opened the case and saw the vert. cam gear was stripped.
-Cannot move chain manually more than a couple of inches
-With the button pushed the gear runs stripped and when I pull the chain manually(major pulling), I get a little movement " 4 ft" before it cuts off, 15 sec.

I bought a rental property with a Craftsman 139.53970SRT opener. One torsion spring was broken so I had both replaced. Apprantly the large plastic white gear inside the opener is the weak link designed to strip under a load instead of burning up the motor when a torsion spring breaks. I replaced the gear plus the worm gear. All back together but the motor only runs about 2 seconds then reverses direction. On the door sensors, one is green and one is yellow. Are they supposed to both be green?

Nope, one should be green and one amber. U might try messing with the up and down adjustments on the side of ur machine.

I have just installed a new Craftsman 1/2 HP opener, model #53920. When I push the wall button the door will close about 3 inches and then reverse and the light clicks 10 times. If I hold the wall button down it will close all the way. Have not had a problem with it opening once closed. Any help would be appreciated.

mb.you need to correct the installation/alignment of the door sensors.

Hi, Glad I found this forum! I have a Craftsman 139.53661 SRT and it stopped working. It just hums and then stops, even if it's not attached to the door. The led light blinks yellow 5 times. The other door has the same model and it blinks yellow 5 times while it's working, but it WORKS so I'm not sure that the blinking is indicative of anything. Thanks for any help you can provide.

Hi, I have a Craftsman 1/2 HP. Using the suggestions in this forum I already repared it once a month ago by replacing the worn-out drive gear. It worked for a month but stopped working all of a sudden today. It opened the door about 3 feet and stopped. I adjusted the chain because it was drooping too much. That made no difference though. The engine hums but the chain doesn't move at all. The light does not blink either when the engine stops humming. Last time, when the worn-out gear was the issue, it did. Any idea what the problem could be this time? Could the new gear wear out so fast?!

Thanks in advance for your help.

Its possible the pin that holds the gear in place has slowly worked its way out or broke and now it isn't turning the gear at all. I would start looking there.

Thanks for the reply jla74...It turned out that the chain was not mounted on the sprocket! It had come loose and fallen off. Now I have to find out why it became loose. I think I might be missing a part where the two ends of the chain come together. There's a bolt on each side: inner and outer. Should there be a stopper or something to hold them in place so they don't turn an gradually loosen the chain?

I just noticed that my garage door opener chain is sagging....since we have 2 and the other isn't doing that, I figured this wasn't good. Is fixing this as simple as tightening the screw at the end of the chain? Any reason it might sag like this?
Thanks for your help!

I have a 139.53644SRT.... wall module opens/closes door without a problem but neither remote is working. HELP! Background - I set vacation mode, came back and turned that mode off (no more flashing lite), but remote did not work. We tried using manual to reset control codes...that didn't work either. What to do?

First thing I would try is unplugging the unit from the power source for a few minutes to see if it will reset. Then because your remotes worked before you set vacation mode and then turned it off I would eliminate the wall control. You can do this by removing the wire from terminal 1 on the back of the motor unit. Also try programming the opener. Have you had lightning in the area? Added anything new to the garage?

I am getting ready to sell my house and the appraiser told me that the garage door opener is not functioning correctly because it does not automatically retract when it encounters something while closing.

The type of opener is Craftsman Garage Door Opener 1/2 hp Chain Drive, Security+ Anti-Burglary Coding, Sears Item# 00953930000 : Model# 53930

Does anyone know if that means I need a new one or if there is an adjustment I could make to the opener to fix this?

Thanks...

This form helped me get my garage door opener working again! Thanks for posting helpful advice.

I have a 10 yr. old craftsman garage door opener that has slowly over time decreased in range that it worked. Now it works only very close to the antenna and further digressed to 1 per 50 successful operations. It works great with the wall button. I tried a new remote with the same results. Batteries have been changed in all devices. Thanks in advance for any hints.

my son pulled the red rope hanging from the garage door openenr and now I cant get the door to close. It looks like the chain has come off of the track bracket (dont know what its called, its what runs along the track). Ahy help as my BF is 4 states away right now.

“Is real tight” mentioned tighter than the door that works well? If so, ck the load or weight of the doors with spring assistance for the same weight. I am questioning drag or load on the problem door. They should be the same as low weight or the cable might be stretching. Age of doors might need oiling rollers Etc. Foundation shifting might be an issue. Look close and good at both ends of track and share Pics of both ends.

Next is quality of materials with today’s workmanship. Since mid 1980 I have learned all chain vs chain and cable are better. Plus, steel sprockets are better. I have originals given to me in the mid 80s, “oiled and maintained” as noticed from sounds or changes...