Check the following points to resolve the issue:

• Check the machine's environment. Conditions such as high temperatures and high humidity can increase the amount of background shading.
  Refer to Product Safety Guide available on the Manuals section.
• Clean the drum unit.
  > Click here to see how to clean the drum unit.
• Replace the toner cartridge with a new toner cartridge.
  > Click here to see how to replace the toner cartridge.
• Replace the drum unit with a new drum unit.
  > Click here to see how to replace the drum unit.