Hello,

This problem could be due to different components in the printer. First Make sure your supplies levels are ok and replace if necessary. Once you have done that then check the transfer roller in the back door of the printer and make sure is properly seated. Also check the Transfer Drum cleaner brush on top of the printer and make sure that is seated correctly. Here is a link that will take you too a detailed guide on how to check those parts.
http://bit.ly/bZNIc0