Please check the following points to solve the problem:

• Make sure that you use paper that meets our specifications.
  Please refer to FAQ, "What kind of paper can I use? " and "What is the recommended paper?".
  
  
• Check the machine's environment. Conditions such as high temperatures and high humidity can increase the amount of background shading.
  Please refer to Safety and Legal pages in User's Guide.
  
  
• Put in a new toner cartridge.
  Please refer to the instructions, "REPLACE TONER".
  
  
• Put in a new drum unit.
  Please refer to the instructions, "REPLACE DRUM".