can a crock pot go bad? We have a late 1970s/early 1980s slow cooker (Hamilton Beach Crock Watcher), inherited from my in-laws, that we used to use on roasts, pork loins, etc. and get incredibly tender, easy-to-shred, falling-off-the-bone results pretty regularly.

Lately, everything we cook seems to come out tough, though it sure seems like we're cooking the same cuts and recipes for the same lengths of time... Stuff gets cooked through, it just doesn't turn out as tasty and tender.

Is this possible or are we just losing our minds?
Depending on the design, the heating coil may have collapsed and is shorting out at various points

This may cause it to run hotter than intended, and result in problems you describe

Measure the current with a meter and compare to manufacturers label, if much higher it's time to scrap it. Unlikely to be easily repairable if it has a heating coil

If it is running hot it is likely to fail soon and not heat at all

Modern crock-pots used solid elements, not coils. They also often have physical temperature regulation systems, not just a simple element selector switch