Ok the likely and most common problem is going to be the magnetron, To test the magnetron follow the directions below.
Make sure to discharge the capacitor first.
Do this by touching the blade of an insulated-handled screw driver to one terminal, then slide it toward the other terminal until it makes contact and hold it there for a few seconds. (This can result in a rather startling "pop!")
Carefully remove all leads from the magnetron terminals. Proper wiring is important so make notes of the wire locations.
Set the ohmmeter to its lowest resistance scale.
Measure the resistance from one magnetron terminal to the other in either direction.
The magnetron filament resistance should be less than one ohm.
With the meter set to the highest resistance scale, check from the magnetron terminals to the metal magnetron housing. (Be careful not to touch the meter leads as this will result in a false reading).
The meter should read infinity (open circuit) regardless of meter polarity.
Even a slight reading would indicate a defective magnetron
If the magnetron is bad click the link below to order the new part.Click here
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