If the motor will run one way, it should run the other way. The directional rotation of the motor is changed by reversing the flow of current into the motor, this is done thru the switch. If you reverse the polarity of the leads gong into the motor, its direction should reverse as noted above. If the motor runs using this technique, the motor is fine. Check the wiring to it. If this car sat for a long time, sometimes a door can become ungrounded because of corrosion. Doors are grounded thru the hinges, if they are rusty, that could also be your problem.