Updated 21/05/2024


If your printer is leaving black lines on the page when you print, or dirty streaks/blank areas across the page, we can certainly help!

If you’re running low on time or have an important job to do, this issue can be very frustrating, but it’s one of the most common printer issues that many people experience.

The good news is that the issue can be fixed! Read on to find out how.

The image above gives an example of black lines printing down the page. If this is happening with your Brother, Canon, HP, Lexmark, Oki or Xerox printer and you’re looking for a solution then read on….



Here’s what you’ll learn about printers & black lines


Here are some quick links to help you find the correct solution or the information that you need:

  1. What causes black lines or smudges down the page.
  2. How to fix the printing black lines issue.
  3. What causes horizontal lines when printing and how to fix them.
  4. What causes faint or missing lines and how to fix them.



What causes black lines or smudges down the printer page?


There are several reasons that your printer might be causing black lines or smudges down the page when you print and we’re going to address each one in turn in a process of elimination to help you to fix your problem.

Here are some of the different printer problems and examples of what they look like:

  1. Black vertical lines or tracks on either side of the page, sometimes in the middle.
  2. Missing areas of print (either always in the same place or not).
  3. Smudges on the page (either always in the same place or not).
  4. Horizontal lines across the page.



Horizontal or missing lines on a printout:


Horizontal lines caused by an inkjet printer


Here’s why it happens & how to fix smudges or lines down your printout. First, run a printer clean process to see if it’s a quick fix, you’d be surprised how many times that works. If it didn’t try the following:


Vertical Black lines or tracks down either side of the page.



Inside the printer, the paper is moved along by rubber rollers and in laser printers a piece of film is like a conveyor belt (called a transfer belt). This happens when the rollers or the transfer belt inside the printer get dirty or covered in excess dirt, ink or toner powder, and as the paper is moved through the printer the ‘tracks’ are being left on the page.

This is normally the case when the tracks on the page are located at either end. If the tracks are located all over the page or even in the middle, it could be due to marks or damage to the transfer belt.

Also, if a blob of dirt or old toner is stuck to a roller or the transfer belt, it smudges a line down the paper as it passes.


The following steps will help to fix this issue:

  1. Get a lint-free cloth, rubber gloves (so toner doesn’t get on your hands), some isopropyl alcohol, and a soft paintbrush and gently clean any rubber rollers you can easily reach.
  2. With a vacuum hoover out any loose toner particles.
  3. With a lint-free cloth very gently wipe the transfer belt (not all printers have one).
  4. If all else fails, you may need to replace the transfer rollers/transfer belt.

Warning: make sure you wear gloves and don’t touch the transfer belt film with your fingers or the hoover, you could leave a mark that will cause additional print problems.

Remember to be careful and if you are at all unsure, find a printer technician who is experienced in cleaning the printer.



Missing areas of print (either always in the same place or not)



There are a few possible causes of this so you may need to check each in a process of elimination to figure out what’s happening but in most cases, the problem is caused by the drum.

The laser printer works by a laser beam ‘sketching’ the image of what you are printing onto a green metal cylinder called a drum or photoconductor unit. The drum then rolls the toner onto the paper as it passes.

A drum is a replaceable maintenance part of the printer and can either be built into the toner cartridge or separate from the toner located on top of or underneath it.

If the drum is damaged in any way with a fingerprint or dirt on it, it can cause sections of the printout to be missing because the dirt is blocking your image from being rolled onto the page.

It can also be caused by a damaged or dirty mirror that reflects the laser beam or it can be caused by a damaged fuser unit.

The fuser is a replaceable maintenance part in the printer that melts the toner so it stays on the page. It also applies pressure so if some part of it is damaged, it can stop the toner from staying on the page.


Unfortunately, these maintenance parts can’t easily be cleaned but the following steps may help to fix this issue:

  1. Replace the toner if you have a new one spare, it could be defective or running out.
  2. Replace the drum unit – this will fix the problem most of the time.
  3. Replace the fuser unit.

Warning: Never touch the green metal cylinder (drum unit)

Once again, remember to be careful and if you’re not sure, get some help.



Smudges on the page (either always in the same place or not)



Smudges in the same place – If you see smudges across your page and they are always in the same place, then that normally indicates some damage to either the drum or the rollers (see problem 2 above for a definition of the drum). It could also potentially be a roller.

What’s happening is that the drum or rollers could have a fingerprint or dirt that is smudging the toner on the page as it passes through to the fuser. It is normally caused by the rollers.

Smudges in different places on each print – If the marks are always in different places, then it’s most likely to be a faulty drum, or that the toner cartridge is leaking on to the page causing black streaks.

This can happen if the cartridge has been in an area of high humidity and toner has absorbed moisture causing it to deteriorate / clump together and damaged the cartridge or drum. Toner cartridges have a 2 year expiry date if stored and if opened, only tend to last around 6 – 8 months.


Have a look inside the printer and see if you can spot any dirt on the drum or any of the rollers that might indicate a problem. Follow the steps below in turn and do another print before the next step to eliminate the problem.

  1. Clean the rollers
  2. Replace the toner if you have a new one spare, it could be defective or running out.
  3. Replace the drum unit.
  4. Replace the fuser unit.

Be careful and again if you’re not sure, get some help and don’t forget your gloves so you don’t get toner on your hands.


Printer missing lines on an inkjet printout

Inkjet printers (that use liquid ink), work totally differently than laser printers (that use powdered toner) but we still get the same issues. So if you have horizontal lines when printing with ink, it’s normally caused by a blocked or clogged print head. 

You can find the full explanation and how to fix it in our article, ‘Why is my printer printing lines’.


Missing lines down or across the print on a laser printer

If you have missing lines down the page whilst using a laser printer, this is normally down to a damaged drum or fuser. You can find the full explanation and how to fix it on our page; How to fix a laser printer printing lines.


Hopefully, any of the solutions listed in the different types of problems with print above will have fixed your frustrations, but if none of the above steps works then it could well be a much more serious problem with your printer and it might be time to think about a new one!


Did this article help you out? Let me know in the comments, or if you just want to ask anything else, get in touch and comment below!

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