Have you already tried replacing the drum unit?
NOTE: The Drum Cartridge is a Customer Replaceable Unit (CRU). After approximately 60,000 copies / prints, the machine will display a warning message before the Drum reaches the end-of-life. Make sure to have a replacement cartridge available.
To remove the old Drum Cartridge:
To install the new Drum Cartridge:
CAUTION: When replacing the Drum Cartridge, make sure that the new cartridge is the correct cartridge specified for the machine.