Sebastian S Sanford , MI June 07, 2022 Microwave oven interior caught fire. After some online research. we determined that the cause of the fire was the waveguide cover. The instructions on the AppliancePartsPros.com website confirmed this and I ordered the replacement part. It arrived three days later and the microwave oven was up and running that evening. Do-It-Yourself Rating: Repair Time Estimate: 30-60 minutes