The bottom most switch or its plastic actuator tend to be the problem if it is door switches. The mini-manual should help with that. Range Hood model? Plug it into a GFI and see if the GFI trips. I've had this on a couple of GEs. The turntable and stirrer motors are 21VAC motors and get the low voltage from a tap on the main fan motor. The wire to the tuntable gets pinched and completes the circuit to the fan and lamp by grounding out.
Thanks for your response. By mini-manual, do you mean the one that came with the microwave or are you referring to something else. I don't see anything in my manual that speaks about door switch or latch problems. I'm not having problems with the turntable at all. Only way I could plug this unit into a GFI would be to run an extension cord. Is that OK?