Microwave cavity paint is peeling or rust is visible inside.

Safety note: Exposed rust and metal can lead to arcing. Address promptly.

User-level steps:

• 1. Clean and dry: Remove all loose paint and rust flakes with a non-metallic scraper and clean the area.
• 2. Sand lightly: Lightly sand rusty spots to remove loose material, then wipe clean.
• 3. Apply microwave-safe touch-up paint: Use a cavity touch-up paint rated for microwave use to cover bare metal. Allow to cure fully per instructions before using the microwave.

If rust is extensive or structural metal is compromised, replacement of the microwave is recommended.