http://www.brother.com/eu-printer/faq/1040-gen.html Why do I have faint print or marks on the printout?
The printer and drum unit may need to be cleaned. Use the following steps:
Turn off the power switch located on the left side of the printer.Open the top lid of the printer. Use caution, as some parts of the printer may be hot.
Lift the drum unit out of the printer (do not remove the toner cartridge) and set on a scrap paper.
Tilt the drum unit up slightly to view the bottom of the drum unit. Slide the blue tab (corona wire cleaner tab) back and forth approximately 5 times. Make sure the tab is returned to the home position (under the black arrow) when finished.
With a soft, DRY cloth, wipe the scanner window and toner sensor. The scanner window is located on the floor of the printer cavity, directly across the middle of the printer. It is a small glass piece, approximately 1/4-in. wide. The toner sensor is located on the floor of the printer cavity, towards the back. It is a \"U\" shaped, black plastic piece. Wipe between the posts of the toner sensor.
Replace the drum unit, close the printer, and turn the power back on.
Try printing about five pages.
If the pages still shows signs of poor print quality (such as black smudges, black dots or faded print areas), the drum unit may need to be replaced.
NOTE: DO NOT use rubbing alcohol or any other fluid on the scanner window or the toner sensor. Both the drum unit and toner cartridge contain toner. If toner gets on clothing or hands, wipe immediately or wash with cold water.