Countertop microwaves are usually not worth repairing — a new one is often cheaper than the part. Built-ins and OTRs are a different story: replacing the unit means a custom trim kit, a new install, and sometimes new cabinetry.
Common fixes
- No heat, lights work — magnetrons, diodes, capacitors, high-voltage transformers
- Dead unit — door interlock switches, thermal fuses, line fuses, control boards
- Noise / sparking — waveguide covers, stirrer motors, turntable motors
- Touch panel unresponsive — membrane keypads, control boards
Safety note: a microwave capacitor holds a lethal charge even when unplugged. Please don’t open one up yourself.