Update:
finally got around to taking the old winch off the trailer today. A number of teeth in the gears were rusted out, completely missing- no wonder it failed under load!
thanks for urging me to replace it, will do it this weekend.
Joe
Since I don't have a trailer parts store or marina close to me, I got a winch at Wally World- Reese manufacturing company. Anyone know if these are any good?