Visible arcing (sparks) inside the cavity, often near the side wall or around the turntable.

Immediate action: Stop the microwave immediately and unplug it. Do not continue to run the unit while arcing occurs.

Steps:

• 1. Remove metal objects: Ensure no metal containers, foil, or utensils are inside. Use only microwave-safe cookware.
• 2. Inspect waveguide cover: Check the mica cover for burn holes, cracks, or heavy grease. Replace if damaged.
• 3. Clean cavity: Remove any carbonized food deposits or grease, especially in corners and around the waveguide area.
• 4. Check cavity coating: Look for chipped or exposed metal areas. Small chips can sometimes be touched up with microwave-safe cavity paint; larger damage requires professional assessment.

After replacing the waveguide cover and cleaning, test with a cup of water. If arcing persists, discontinue use and contact service.