Microwave repair requires extreme caution—the capacitor holds lethal voltage even when unplugged. Wait 24 hours or discharge it before opening. "Runs but doesn't heat" usually means a failed magnetron. Turntable motors, door switches, and high-voltage diodes are common replacements. Our guides cover Samsung, LG, Panasonic, GE, and more. Never operate a microwave with the door open or the interlock bypassed. The waveguide cover (metal plate inside) must be intact to prevent arcing. When in doubt, replace the unit—microwaves are inexpensive.