Scott Halseth, the switch is called Door Sensing Switch, part number WB24X829. There may be more than one. When the door is opened during a cook cycle, the monitor switch, door sensing switch, primary interlock switch and power relay are deactivated. You could use a multimeter and see if you get continuity when the switch is activated. Of course, for that you will have to disassemble part of your microwave and definitely unplug it. Remove the built-in microwave from the wall and keep it in an open space. Remove the microwave screws and take the cover out.Remove the 2 inside screws from the plastic panel where switches are snapped in. As always, this is a microwave and carries quite a punch if not properly service and discharged. Please be aware of this and if you have not done a repair on those, you might consider some professional help with that. Hope this helps, good luck.