If you install a new toner cartridge but the "Toner Low", "Replace Toner" or "Toner Ended" error indication remains, the toner cartridge may not be installed correctly. Reinstall the toner cartridge, referring to the instructions on how to replace the toner cartridge. ...
To keep good print quality, the Brother machine detects the quality deterioration of the drum unit automatically. If the Brother machine displays "Replace drum" error message, you need to replace the drum unit. [Example 1] The drum unit of monochrome laser model MFC-7840W ...