DIAGNOSIS The door hinge assembly or latch mechanism is worn or out of alignment. This can affect the door switches that allow operation.
FIX Inspect the three door latch hooks on the inner door edge. Ensure they are not chipped or broken. Check the corresponding latch slots on the oven front. Clean any debris from the slots. Tighten the two screws at the top and bottom of the hinge side of the door.
IF THAT DIDN'T WORK The door switch assembly may be failing. A misaligned door may not fully depress the primary safety switch. This will prevent the microwave from starting. The switch assembly requires replacement.
HEADS UP Do not operate the microwave if the door does not seal firmly. The primary safety interlock switches must engage fully to prevent microwave energy leakage. If in doubt, discontinue use.