First, do you have a good ground and enough juice at the windless? You need not just volts, but enough amp capacity in the connection.

Then, I would try to bypass the solenoid/control box and see if it's the motor and gear box. First in normal, then in reverse.

If it works, then it's the control box, switches, or wires between.

If it doesn't work, then it's motor, spindle, or gearbox.

That's would be my course of trouble shooting.