I watched "appliancepartspros" videos on You Tube and followed the recommendations. On three occasions in the past 6 years I have needed to repair our microwave when it failed to heat. In all situations it was either the magnetron, capacitor, high-voltage diode, or a failure of the high-voltage diode terminal screw to make a good circuit with the microwave frame. ( I keep photo files of repairs for appliances, plumbing, etc. that I may need to revisit again to speed-up possible future repairs.)