Microwave interior shows sparks or arcing during cooking, often near the side wall or waveguide cover.

Safety: Stop the microwave immediately and unplug it.

Cleaning and inspection:

• Inspect the waveguide cover (mica or plastic panel) for burn marks, holes, or cracks. Replace if damaged.
• Clean the cavity thoroughly with a mild detergent, paying special attention to areas where arcing occurred.
• Do not use metal containers, foil, or dishes with metallic trim.

Paint/rust repair:

• If paint has flaked off and metal is exposed, sand lightly and apply microwave-safe cavity touch-up paint as recommended by Neff.

Do not use the microwave until the waveguide cover is replaced and the cavity is clean and undamaged.