Hey Guys, having a hard time with my 1991 GMC Jimmy windshield wipers. They function for about 20 minutes, then stop. I have replaced the motor, there is no binding in the wiper motion, and nothing gets hot. This new motor seems to be too weak and I can help it so it moves the wipers. Seems like only 1 speed is operating. Would that be the switch as a problem? And I am looking for a better motor than this China junk, any suggestions?