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

Safety first: Unplug the microwave before any internal inspection. Avoid contact with high-voltage components.

Steps:

• 1. Isolate the source: Run the microwave with a cup of water and listen carefully to locate the noise (top, side, rear, or bottom).
• 2. Check turntable system: Remove the glass tray and roller ring. Clean and inspect for cracks or debris. Run briefly without the tray to see if the noise changes.
• 3. Inspect fan and mounts (experienced DIYers): Remove the cabinet and check the cooling fan motor, turntable motor, and transformer mounts for looseness. Tighten screws and ensure no wires are contacting moving parts.

Note: A deep, loud hum often indicates a failing magnetron or transformer, which should be replaced by a professional.