I ordered the capacitor, diode, and magnetron in hopes that I would be able to complete the repair using the less expensive parts. I first removed the oven from the wall and then I removed the metal housing to access the internal parts. I discharged the capacitor using a pair of insulated needle nose pliers. Then I changed out the diode and the capacitor and reassembled the unit and tested it. It still did not heat so I disassembled the unit again and replaced the magnetron this time. Reassembled the unit and tested it and this time it worked. With the excellent 365 day policy from Appliance Pro Parts you can return the unneeded parts.