Hi Joe,
The first thing I would test is a secondary interlock switch (#2 on the latch board break down diagram)
If the switch is fine then the question is: does your microwave make any unusual noise?
If it does then most likely the problem is a shorted rectifier (#9 on the magnetron and the air flow break down diagram) or a shorted magnetron tube (#1 on the magnetron and the air flow break down diagram. If there is a continuity across the rectifier terminals (using a regular meter) - it has to be replaced.
If there is a continuity between any of the magnetron tube terminals and the body of the magnetron tube - it has to be replaced.
In case if the high voltage transformer shorted out, in most cases it should produce an electrical burning smell and a smoke.
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The break down diagrams for the Whirlpool microwave Model MH7130XEQ1
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The part number for the door interlock switch kit is [COLOR=#0000ff]AP3109474[/COLOR]
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The part number for the rectifier is [COLOR=#800080]AP3955781[/COLOR]
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The part number for the magnetron tube is [COLOR=#0000ff]AP3081175[/COLOR]
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The part number for the high voltage transformer is [COLOR=#0000ff]AP3081176[/COLOR]
Good luck.
Gene.