No, unless someone gets ahold of them and grinds them down, for some reason.

I've used mine for close to 40 years, and got them used. the only things that I've replaced were the gasket and the pressure relief plug (little rubber disk looking thing).

Try them out with some test jars (colored water), and watch carefully. Otherwise, they should be good.

I'll be inheriting my grandmother's canner, she died in 1956, so I'll be working on updating the gaskets and such.

Some different terminology for clarification - they are weights or gauges, not weighted gauges, ok? Some models have only a gauge, some only a weight or set of weights, and some have both a gauge and a weight set.

No the weights never go bad assuming they are the right one for the model/brand of canner.

However the gauges do go bad - some are off by several pounds right out of the box - which is why having them tested/recalibrated annually is so strongly recommended.

If you want to use the 12 qt. Presto then we usually suggest you buy the 3 piece weight for it rather than rely on the gauge unless of course you are at an altitude where you have to can everything at 15 lbs. in which case you can use the 15.5 lb counterweight on it. I am assuming it will hold the 4 quart jars minimum to qualify as a pressure canner rather than just a pressure cooker?

Personally of the 3 I'd use the 22 quart Mirro given its size and because gauges just can't be trusted.

Dave