Open the front door.
Warning—Potential Damage: To prevent damage from electrostatic discharge, touch any exposed metal frame of the printer before accessing or touching interior areas of the printer.
Remove the imaging unit.
Remove the used toner cartridge from the imaging unit.
Unpack the new toner cartridge.
Shake the toner cartridge to redistribute the toner.
Remove the seal, and then remove the cover.
Insert the new toner cartridge into the imaging unit.
Insert the imaging unit.
Close the door.
Avoid printing delays. Install a new imaging unit when the printer prompts you to replace it.
Check the paper settings in the print dialog and in the printer to get clean prints. Reinstalling or replacing the imaging unit may also help solve this print quality issue.