Microwave makes a rattling, grinding, or scraping noise when the turntable rotates.

Safety first: Unplug the microwave.

Mechanical inspection:

• Remove the glass tray and support ring; clean the cavity floor thoroughly.
• Inspect the roller ring for flat spots, cracks, or missing rollers; replace if worn.
• Check that the glass tray sits flat and engages the coupler properly.
• Run the microwave briefly (with water) without the glass tray to see if noise persists; if so, the motor may be noisy and should be replaced.