| Bent Pins/Loose Connectors?
I have only dug into one of these in class, but I recall that it was mechanically pretty unusual for a bypass tray.
I think I'd start out by pulling th MPT and re-seating every connector I could find, especially the motor, and where it connects to the controller.
I'm sure you already turned through by hand to feel for any excessive resistance/drag on the drive. If I recall correctly there are lift cams that use the same drive. It took me a few tries to get that reassembled so it would work. | 
Linear Mode
