I'm sorry if this has been posted before. I tried searching here and on Google, but couldn't figure out what I should even be searching for.

I'm attaching a photo to illustrate what is happening when we print. There are white streaks that appear equally distant apart. I tried taking out the drum unit and inspecting the head, but I don't see anything that would be causing this on the actual unit.

It is a Brother HL-3170CDW Printer.

Thank you for any help anyone can offer.

enter image description here

  • If you print this exact image again, do the white streaks appear in the same spots?
    – Tim G.
    Jul 21, 2016 at 20:53
  • It appears in a different place horizontally. Vertically is the same. Jul 21, 2016 at 21:01

1 Answer 1


If you're printing in landscape, then one or more of the drum units are likely to be the cause of the issue. Try cleaning the drum with a damp cloth and see if the problem persists. Alternatively, your transfer belt might be damaged; remove all the toner cartridges and drums and check if the belt is physically damaged in any way.

I wouldn't be able to explain the issue if this is happening in portrait. As far as I know, this printer feeds sheets in portrait orientation, and repeating print quality issues should only happen in the direction the paper is traveling. It's possible that some other part like the laser scanner is failing, but I can't say for sure.

  • This is happening in portrait. What's the safest/best way to clean the drum unit? Jul 21, 2016 at 22:15
  • I'd take a clean cloth, wet it with water or isopropyl alcohol (the latter is better), and wipe the surface of the drum. Use the white gear to rotate the drum as you clean it. Avoid exposing the drum to light for too long as doing so can damage the drum.
    – bwDraco
    Jul 21, 2016 at 22:34
  • I finally got around to checking the transfer belt, and apparently someone has managed to put a dent in it. Thank you for the sound answer! Aug 4, 2016 at 17:24
  • 1
    The transfer belt is part BU-220CL.
    – bwDraco
    Aug 5, 2016 at 1:03

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