Originally Posted by Bob_B

David if you have a battery you can simply plug it into the retract to make it cycle, if it does not move reverse the connection. If it will not move with the battery connected either way i'd say the motor is shot, but these unit are really robust.
If you are concerned about overvoltage use a regulator or lower voltage source. All sensing is done in the control box so DON'T over drive the the retract.