1990 DL240 Wagon

My rear window wiper never stops in the same place when turned off at the switch. I watched the motor with the trim panel removed. The intermittent setting, just moves the blade a little bit then stops.
My thinking is the park switch is somehow defective. Before I remove the rear wiper motor, does anyone know if this is repairable or am I looking at buying a new motor?

Thanks in advance.