DIAGNOSIS A mechanical component is binding or lacks lubrication. The primary suspects are the fuser unit gears or the paper pickup roller assembly.
FIX Isolate the noise phase. Open the rear cover. Print a single page. Listen. If noise occurs during paper pickup, the issue is in the paper tray assembly. Remove the tray. Inspect the white pickup roller for wear or debris. Clean it with a damp cloth. If noise occurs during printing, the issue is internal. Power off and unplug. Remove the toner and drum. Inspect the large green fuser drive gear through the opening. Check for cracked teeth or foreign material.
IF THAT DIDN'T WORK The fuser unit itself may have a failed bearing. This requires fuser replacement. Confirm by removing the fuser unit (after printer cools). Manually rotate the fuser roller. Any grating or resistance indicates bearing failure.
HEADS UP The fuser unit is extremely hot during and after operation. Allow 30 minutes of cool-down time before internal inspection or removal.