Microwave runs but makes loud buzzing or humming noise, louder than normal

Safety first: Unplug the microwave before any inspection. Loud buzzing from HV components can indicate imminent failure.

• 1. Stop using the microwave: If the noise is significantly louder than usual or accompanied by a burning smell, discontinue use.
• 2. External check: Ensure the microwave is level and not vibrating against cabinets or walls, which can amplify normal noise.
• 3. Internal inspection (advanced): With the cover removed and unit unplugged, check that the transformer and magnetron mounting bolts are tight and that no metal parts are loose.
• 4. Professional testing: A technician should test the transformer, magnetron, and capacitor. Replace any component that shows signs of overheating or electrical breakdown.