Maybe the gears are worn down and the teeth are just tapping something to make the clicking sound. Or the motor is dead and it is just the actuator clicking?
I had a problem with my warn winch, so I took it apart cleaned it. I could here it trying to work but wouldn't. Took it apart again and realized that the drive shaft did not engage all the way in. Ordered up a new one and it works fine, if yours is a warn maybe give this a try. Good luck.