Check the following points:

• Wipe the scanner glass strip with a dry lint free soft cloth.

  Click here to see how to clean the scanner glass strip.

  
  

• The corona wire of the drum unit may be dirty.

  Click here to see how to clean the corona wires.

  
  

• Make sure the green tab of the corona wire is at the home position.

  
  

• The drum unit may be damaged. Put in a new drum unit.

  Click here to see how to replace the drum unit.

  
  

• The toner cartridge may be damaged. Put in a new toner cartridge.

  Click here to see how to replace the toner cartridge.