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

Safety: Unplug the microwave if the noise is accompanied by burning smell or smoke.

• Isolate source: Run the microwave with the glass tray and roller ring removed (with a cup of water inside). If the noise decreases, the issue may be with the turntable system.
• Inspect roller ring: Check for cracks, flat spots, or debris stuck in the wheels. Clean or replace if damaged.
• Listen for fan: A rattling or scraping sound from the top or back may indicate a failing cooling fan motor, which requires internal access.
• Professional diagnosis: A loud electrical buzzing can indicate a failing magnetron or transformer. These should be tested and replaced by a technician.