This is a microwave repair question. The start button on the membrane switch panel that controls the timer and manual cook defrost settings works intermittently. I assumed since it is the most used button, that it has worn out but you know what they say about assumptions. Then I thought it might be door switch but the sensor controls atop, that do not depend on the start button to operate, operate flawlessly. Do you think it is the door switches or the membrane control panel or something else?

Also I noticed that there are three door switches but they are ordered on in pairs? Do I guess which is bad or replace all? Thank you.

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