DIAGNOSIS A sustained grinding or loud ratcheting noise is usually something physical in the paper path. The most common culprits are a foreign object (like a stray paperclip) or a worn pickup roller assembly grabbing paper awkwardly.
FIX Power off and unplug the printer. Open all the doors—front, rear, and the duplex unit if you have it. Visually inspect for any debris or crumpled bits of paper. Remove the toner and drum to look deeper. Also, check the paper in the tray isn't overloaded or curled, causing the rollers to slip and grind.
IF THAT DIDN'T WORK If the noise seems to come specifically from the right side during printing, the fuser gear might be the issue. This isn't a user-serviceable part, but confirming the location helps. If it's a rhythmic grinding tied to page movement, it's likely a professional repair.
HEADS UP Don't keep running it with a bad grind. You can turn a simple paper jam into a stripped gear or damaged fuser, which is a much more expensive fix.