Turntable not spinning - GE Spacemaker XL1800
I've got a GE Profile Spacemaker XL1800, Model JVM186SD002. The turntable is not spinning when there is any weight on it. If I leave the microwave empty, the plate spins very slowly. If I put anything on the plate, it does not spin at all. When it tries to spin, there is a loud whrrring sound.
I've looked for a repair manual, but cannot find one. Can someone please help me out with this repair? I really don't want to have to replace the whole unit.