Open door A.
Remove the used toner cartridge.
Unpack the new toner cartridge, and then shake it three times to redistribute the toner.
Insert the new toner cartridge.
Note: Use the arrows inside the printer as guides.
Close door A.
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.