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

Safety first: Immediately stop the microwave by pressing Stop/Cancel and unplug it if you see sparks.

Steps:

• Remove metal objects: Ensure there is no metal cookware, foil, twist ties, or utensils inside.
• Inspect waveguide cover: The waveguide cover is usually a small rectangular mica or plastic panel on the side wall. If it is burned, cracked, or has holes, it must be replaced.
• Clean cavity: After the unit cools, clean the interior thoroughly with mild detergent and water to remove grease and carbonized food. Dry completely.

If arcing continues or the waveguide cover is damaged:

• Do not use the microwave until a technician replaces the waveguide cover and inspects the cavity for damage.