Mark,
I have the same exact lathe, but in a 48" bedlength model (model #25-750, if I remember correctly). The problem with the power crossfead is most likely due to a worn out brass worm gear inside of the apron. You can easily disassemble the apron and check if this is the case, it is fairly foolproof and there are not a lot of small parts, etc. to lose or come out unexpectedly. I have disassembled mine 3 times since I bought the lathe and it is quite easy to do. The whole apron gear assembly comes off the lathe completely if you undo the end of the long leadscrew, at the tailstock end of the lathe, then slide the whole thing off the end of the lathe.
It would be a good idea for you to disassemble the apron section of the lathe anyway, so that it can be cleaned and inspected. It would only be a 2-3 hour project, including cleaning, and will reward you with information about your lathe and how it works - as well as figuring out if the brass wormgear is what is truly at fault.
One other thing, just as a thought. If you find that it is the brass wormgear that is the problem, we could go in together on possibly obtaining a discount for having 2 or 3 of them made at once. Mine is rather worn, although it still works, and I would like to have a spare or two around for when it finally does fail.
Best regards,
Bawko