The first symptom was our microwave would continue to run after the time was up. The light would go out, the turn table would stop but you could still hear the microwave running and whatever was in it would continue to cook. The only way to stop it was to open the door. It was intermittent at first but eventually it would always run no matter what as long as the door was closed. Several other posts referenced these switches as the problem. I just replaced both and problem gone. It turns out there are actually 3 door switches. These 2 were on the bottom latch. FYI, the difference between the 2 switches is one is NO (normally open) and the other is NC (normally closed) - be sure you don't mix them up.There was one on the top latch (which I wasn't aware of until I took it apart) that I did not replace but apparently was not the issue anyway. Had known I would have replaced it as well because these switches tend to fail in any application over time.
This is an easy repair and well worth the time if the microwave is otherwise in decent shape. Just be careful removing the switches from the plastic housing on the door latch. The new one will easily slide in its place and "click" into position but to remove the old one you need to gently lift the plastic tab on the housing that snaps into the tiny hole in the corner of the switch to hold it in place. See this hole on the new switch to know where to look to "release" the old switch. I small flat head screwdriver worked for me. That and a Phillips head were the only tools needed. Hope this helps.