Microwave interior shows sparking or arcing, especially near the side wall or around the waveguide cover.

Immediate action: Press STOP/CLEAR and open the door. Unplug the microwave.

Inspection:

• Remove any metal objects, foil, or dishes with metallic trim from the cavity.
• Inspect the waveguide cover for burn marks, holes, or heavy grease. Replace if damaged.
• Check the cavity walls and ceiling for chipped paint exposing bare metal. Touch-up with microwave-safe cavity paint if minor; if severe, discontinue use.

Do not operate the microwave with a damaged waveguide cover or exposed metal surfaces, as this can damage the magnetron.