sharp microwave trips the breaker once every morning (first use).

it trips the breaker when opening the (sliding tray) door, first time in the morning. then it works fine all day until the next morning when it happens all over again.

it maybe worth mentioning that, the original cause was a bad door switch that was replaced and seemed to work fine afterwards, however now I've learned that after a few hours of no use (like over night), it trips when opening the door again. Once every morning, very frustrating.

I can't find any discoloration on the boards

Thanks for any help