Please check the following points:

• Make sure that you use paper that meets our specifications. Rough-surfaced paper or thick print media may cause this problem.
  To see what kind of paper you can use, click here.
  
  
• Make sure that the media type setting in the driver matches the type of paper you are using.
  To see what kind of media type you can use, click here.
  
  
• Put in a new drum unit.
  To see how to replace the drum unit, click here.