I rescued an apparently near-mint OM10 from a charity shop, and now
I've discovered why it was there. The take-up spool doesn't rotate when
I operate the take-up lever, although if I apply gentle pressure it
rotates correctly.

I suspect that this may be due to  the previous owners'
brute-force-and-ignorance attempt to fix a different problem (caused by
using the wrong batteries.)

It's presumably some sort of clutch problem. Is there any hope of
getting it to work again? I'm loathe to spend a lot on it because I
already have sufficient Olympus bodies, but the OM10 is a nice little
camera and it would be a shame to lose it if this problem is easily
fixable.