Original post by: Millie ,
I had the same problem except there was no noise if I took the glass tray out. It only happened when the tray was on the turntable. After reading these comments, I checked the wheels of the turntable. No flat spots or problems there. Finally, I spotted a tiny crumb on the bottom surface of the microwave, right in the ridge where the wheels roll. It was small, but quite hard and white in color…hard to see on the white surface. I removed it and no more rattling!! So wipe out the bottom of your microwave if all else fails!