The Drivers side power seat moves forward about 2 - 3 inches and grinds to a halt. Removed seat and turned it on it's side to examine the tracks and discovered they are traveling at a different speed. This is causing the stoppage. There appears to be one motor with a short shaft coming out one end and a long shaft coming out the other. how can one motor turn at 2 different speeds? Or are there 2 separate motors in one housing? Thanks!