Match your symptom to narrow down the likely cause before calling us.
These checks are safe for homeowners. Do not attempt to open sealed refrigerant systems, touch electrical components behind access panels, or work on gas lines — always call a licensed technician for those.
If you see sparks, stop the microwave immediately. Continuing to run a microwave while it's arcing can cause permanent damage to the cavity walls, char the waveguide cover, and eventually destroy the magnetron. Open the door, let it cool, and identify the source before using it again.
The waveguide cover (the small flat panel on the inside ceiling) is the most common arc source after metallic dishes. Wipe it gently with a damp cloth — never abrasive pads. If it has burn marks or is cracked, it's a replaceable part available from the manufacturer and costs $5–$20.
Before using the microwave again, inspect all containers for metallic trim, twist ties, staples, or aluminum foil remnants. Even very small pieces of metal can cause significant arcing. Use only microwave-safe glass, ceramic, or plastic.
The most common non-metal arcing cause is a burned or food-contaminated waveguide cover — the small rectangular panel on the inside ceiling. Food deposits on it absorb microwave energy and begin to arc even without any metal present. Remove and inspect the cover; if it's stained or burned, replace it. Chipped interior paint exposing bare metal is the other common cause.
Only if you've identified and eliminated the cause. If sparking was caused by metallic items and the interior shows no damage, it may be safe to continue after removing those items. If there are scorch marks, a damaged waveguide cover, or you can't identify the cause, stop using it and call for service — continued arcing can damage the magnetron and create a fire risk.
Yes — small chips can be touched up with food-grade microwave cavity paint (available online for $10–$20). Clean the area thoroughly, apply the paint per instructions, and allow to cure fully before using. Large areas of chipping (more than a few small spots) may indicate the cavity coating is failing broadly, which can make DIY repair impractical.
The waveguide cover part is inexpensive — typically $8–$25 for most microwave models. If a technician replaces it as part of a service call, expect $80–$130 total including the diagnostic visit. HomeHeroes can replace the cover and inspect for any secondary damage from prior arcing in one visit.
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