Hey,
I have this fairly young epi which I grew from a cutting a couple of years ago.
It looks really green and healthy except for the tip of one leaf, which is yellow, scabby and a bit mushy, with these tiny red speckles on it. The problem seems to be getting worse.

I know I haven't overwatered the plant, and I can't find any insects or mites on it anywhere, though I've searched over and over!
One of my other jungle cacti had the same problem last year. I never figured out what the problem was.

Does anybody have any idea what this is?

Thanks very much!
- Sparkey