Troubleshooting
144
7
Black toner marks across the 
page
 The drum unit may be damaged. Put in a new drum unit. See Replacing the drum 
unit on page 113.
 The toner cartridge may be damaged. Put in a new toner cartridge. See 
Replacing the toner cartridge on page 107.
 Make sure that you use paper that meets our specifications. See About paper on 
page 6.
 If you use label sheets for laser printers, the glue from the sheets may sometimes 
stick to the OPC drum surface. Clean the drum unit. See Clean the drum unit as 
follows: on page 143.
 Do not use paper that has clips or staples because they will scratch the surface 
of the drum.
 If the unpacked drum unit is in direct sunlight or room light, the unit may be 
damaged.
Black lines down the page
Printed pages have toner stains 
down the page.
 Clean the primary corona wire inside the drum unit by sliding the blue tab. See 
Cleaning the corona wire on page 124.
 Make sure the primary corona wire cleaner is at the home position (a).
 The drum unit may be damaged. Put in a new drum unit. See Replacing the drum 
unit on page 113.
 The toner cartridge may be damaged. Put in a new toner cartridge. See 
Replacing the toner cartridge on page 107.
 The fuser unit may be smudged. Call your dealer or Brother Customer Service.
White lines down the page
 Make sure that a torn piece of paper is not inside the printer covering the scanner 
window.
 Wipe the scanner window with a soft cloth. See Cleaning the inside of the printer 
on page 119.
 The toner cartridge may be damaged. Put in a new toner cartridge. See 
Replacing the toner cartridge on page 107.
 The drum unit may be damaged. Put in a new drum unit. See Replacing the drum 
unit on page 113.
Page skewed
 Make sure that the paper or other print media is loaded properly in the paper tray 
and that the guides are not too tight or too loose against the paper stack.
 Set the paper guides correctly. See Printing on plain paper, bond paper or 
transparencies from Tray 1, 2 or 3 on page 11.
 If you are using the multi-purpose tray, see Printing on plain paper, bond paper 
or transparencies from the MP tray on page 15.
 The paper tray may be too full. See Printing on plain paper, bond paper or 
transparencies from Tray 1, 2 or 3 on page 11.
 Check the paper type and quality. See About paper on page 6.
Examples of poor print 
quality
Recommendation