First step was to make sure capacitor was discharged before touching other components.Used multimeter (VOM) to check out components, diode, capacitor, and magnetron. Ordered all three as readings were not consistent with expected. Started by replacing magnetron. Tested with cup of water. Viola microwave was heating the water. Returned the other parts. Super service. One caution is to make sure capacitor is discharged before doing any work as it contains high voltage. Safety first.