Does the winch motor get really hot ?
Only 2 winch problems I've had - and that sound you hear is me knocking on wood - is a bad connection at the handheld trigger for my trailer winch, and what I guess was water seepage into the winch motor used on my snow plow.
The plow motor went intermittent and quickly just quit - I merely replaced it, wasn't expensive.
I wrapped electrical tap around the seam of the plow winch and it's been fine since.
Motor does not get hot. I tried it again today and the battery was dead. Will charge the bejesus out of it this weekend and see if that helps, although I kjnow it had a good charge the last time it was doing this...