Microwave runs but makes loud humming, buzzing, or grinding noises during operation.

Safety: Unplug the microwave before inspecting internal components.

Steps:

• 1. Isolate the noise source: Run the microwave briefly with an appropriate load (cup of water) and listen carefully to determine if the noise is from the bottom (turntable), rear (fan), or HV area (deep hum).
• 2. Check turntable components: Remove the glass tray and roller ring. Clean and inspect for cracks or debris. Run a short cycle without the tray to see if the noise changes.
• 3. Inspect fan and mounting: With the cabinet removed (unplugged first), check that the cooling fan blades are not rubbing and that all mounting screws are tight. Replace a noisy or wobbling fan motor.
• 4. Magnetron hum: A very loud, deep hum often indicates a failing magnetron or HV component. Discontinue use and have a technician inspect the HV system.