I pulled off the outer shell to expose the door switches. I metered through the switches with the door open and closed. The bottom switch did not change with alternating door positions as it should. I ordered and received the bottom switch. Switch replacement was easy, push out the tab under the switch and rotate switch down and out. Install the new switch in reverse until it clicks into place. $4.94 for the switch and $7.95 for S/H...total cost $13.15 = microwave fixed!! AppliancePartsPros had good testimonials that helped to diagnose the problem and potential solution.