When buying an FE (FM,FA for that matter) be wary of ones that show signs of a motor drive or winder being attached. The FA is usually missing the front grip and the MD contact cover, they all will (FA,FM,FE) will have burrs raised on the sides of the drive slot.
These cameras probably have had the wind mechanism beat up or more than expected wear on the wind mechanism.
Some people use motors/winders all the time, I only use them when I absolutely have to have one.
I'll second Safety Bob, good condition FEs are worth fixing.