Microwave sparking inside?

Food splatter burned into the waveguide cover creates carbonized spots that arc violently when exposed to microwave energy.

Likely causes · most likely first

Waveguide Cover (Mica Sheet)

Easy DIY Part: $8–$20
Cooking Cavity (Faraday Cage)

Easy DIY Part: $10–$25

Damaged or chipped enamel inside the cooking cavity exposes bare metal that creates arc points in the microwave field.
Magnetron (2M261-M32KLP)

Call a Pro Part: $50–$150

A failing magnetron with internal antenna damage can produce irregular microwave patterns that cause arcing within the cavity.
Roller Ring (Turntable Support)

Easy DIY Part: $10–$25

A metal-contaminated or damaged roller ring can create small arc points if metallic deposits come into contact with the magnetron field.

See the faulty part in 3D.

Tap a highlighted part to see exactly why it fails, how to verify it's the problem, and how to replace it.