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

Safety first: Unplug the microwave before inspecting internal components. Loud buzzing can indicate high-voltage arcing.

Step-by-step checks:

• 1. Isolate noise source: Run the microwave briefly with a cup of water and listen from different sides to locate the general area of the noise.
• 2. Check turntable system: Remove the glass tray and roller ring, then run briefly. If the noise disappears, the issue is with the turntable motor or rollers.
• 3. Inspect fan: With the cover removed (unit unplugged), check that the cooling fan blades are not hitting wiring or panels.
• 4. Look for arcing: Inspect the waveguide cover and around the magnetron antenna for burn marks or sparks during operation (view through the vents, do not touch).

If the noise is from the magnetron or transformer area, discontinue use and have a technician inspect the high-voltage components.