DIAGNOSIS A mechanical obstruction is interfering with the carriage assembly's movement. The sound is typically the carriage motor straining against a physical block.
FIX Power off and unplug the printer immediately. Open the front cartridge access door. The printhead carriage should move freely from side to side by hand. Inspect the carriage rail (the metal rod it slides on) for debris, dried ink spatter, or a foreign object like a paperclip. Carefully wipe the rail with a lint-free cloth dampened with distilled water. Manually move the carriage its full range to check for smooth motion. Plug the printer back in and power on.
IF THAT DIDN'T WORK The carriage belt may be damaged or a plastic guide may be broken. With the printer unplugged, inspect the white plastic belt behind the carriage for tears or teeth that are stripped. Also check for any cracked plastic parts on the carriage itself.
HEADS UP Continuing to operate the printer with this grinding noise can permanently damage the carriage motor or encoder strip. If the carriage does not move freely by hand after clearing debris, the mechanism requires professional service.