Neil, Clint Eastwood, aka, Dirty Harry Callihan said, "A man's got to know his limitations!" That's good advice.
It seems to me from your description that something is slipping. It should be somewhat obvious what that "something" is because this drive is rather simple.
I would suggest that you really give the old eyes another look at what is wrong.....what is slipping and then see if you can find a set screw to tighten.
Plan B would be to get a local ham to have a look at it for you. There's no shame in that.