Laser Printer Streaks and Lines: What Causes Them and How to Fix Each One
Last Updated:Quick answer: the direction and color of a laser printer streak tell you which part is at fault. Vertical black lines in the same spot on every page usually mean a dirty corona wire or a scratched drum. Vertical white lines or pale stripes point to low or clumped toner, or dust on the laser window. Horizontal lines that repeat down the page come from a roller or the drum. Smears that rub off mean the fuser isn't bonding the toner. Work through the fixes below in order — the first three cost nothing.
This guide is for laser printers (toner). If you have an inkjet, see faded or streaky prints and missing lines on inkjet prints instead.
What Do Different Laser Printer Streaks Mean?
Print a page with plenty of solid black and white space — page 2 of our free printer test page is designed for this — and compare what you see.
| What you see | Most likely cause | First fix |
|---|---|---|
| Thin vertical black line(s), same place every page | Dirty corona wire (Brother) or scratched/contaminated drum | Clean the corona wire; then try a new drum |
| Wide dark vertical band | Toner leaking from a damaged cartridge seal or wiper blade | Replace the toner cartridge |
| Vertical white lines or pale stripes | Low or clumped toner, debris on the developer roller, or dust on the laser window | Rock the toner cartridge; clean the laser window |
| Whole page faded, getting lighter | Toner nearly empty or toner save mode on | Replace toner; turn off toner save |
| Horizontal lines or marks repeating at equal spacing | Drum, developer roller, transfer roller or fuser | Measure the spacing — see printer ghosting |
| Gray haze or shading across the background | Worn drum, overfilled or low-quality toner, or damp paper | Replace the drum; use fresh paper |
| Toner smears or wipes off with a finger | Fuser not hot enough or failing; wrong paper type setting | Match the paper setting; check the fuser |
| Streaks or smudges along one edge only | Toner leaking at the cartridge end, or a full waste toner box (color lasers) | Replace toner; check the waste toner box |
| One color missing or striped (color laser) | That color's toner or drum | Swap that color's toner, then its drum |
How Do I Fix Vertical Black Lines on a Laser Printer?
1. Clean the corona wire (Brother and some other brands)
On most Brother laser printers the drum unit has a small green tab on top. Remove the drum and toner assembly, then slide the green tab gently all the way left and right several times. Return the tab to its home position (marked with an arrow) before reinstalling — if you don't, you'll get a new vertical stripe. This one step fixes a large share of Brother streak complaints.
2. Look at the drum
Remove the drum and look at the green or blue cylinder under a light without touching it. A scratch, nick or stuck-on spot lined up with your streak means the drum needs replacing. Keep the drum out of bright light while it's out, and never wipe it with a damp cloth or solvent. See drum unit vs toner cartridge for how drums wear.
3. Swap the toner cartridge
A worn wiper blade or broken seal lets toner escape in a stripe. If a spare cartridge makes the line disappear, the old cartridge was the problem.
4. Check the fuser
If the black line smears when you rub it, or there's toner stuck to the fuser roller, the fuser may be contaminated or damaged — see signs you need a new fuser.
How Do I Fix Vertical White Lines or Faded Stripes?
- Rock the toner cartridge. Remove it and tilt it gently side to side five or six times to redistribute the powder. Don't shake it hard or tip it on end.
- Turn off toner save / economy mode in the printer settings or driver.
- Clean the laser window. On printers with an accessible scanner window, wipe it gently with a dry, lint-free cloth. Some Brother color lasers have an LED-head cleaning procedure in the manual.
- Remove debris. A scrap of paper or a staple stuck against the drum or developer roller blocks toner in a narrow stripe.
- Replace the toner if the page is fading overall — a nearly empty cartridge prints in patchy stripes before it stops completely. See how long toner cartridges last.
How Do I Fix Horizontal Lines on a Laser Printer?
Horizontal lines, bands or marks that repeat at equal intervals come from something that rotates. Measure the distance between repeats with a ruler and match it to the component — our ghosting guide has the full spacing chart. A single horizontal line that doesn't repeat is usually a paper-feed problem — see paper feed and roller fixes.
Why Does Toner Smudge or Rub Off the Page?
Toner is plastic powder that the fuser melts onto the paper at high heat. If it smudges, the fuser isn't doing its job:
- Paper type setting is wrong. Heavy paper, labels and cardstock need the "Thick" or "Heavy" setting so the fuser runs hotter.
- Paper is damp. Moisture pulls heat away from the toner. Use paper from a sealed ream — see how to store printer paper.
- The fuser is wearing out. Fusers typically last tens of thousands of pages; a worn one leaves smudges, wrinkles and ghosting. See the printer parts glossary.
- The first page after sleep smears. The fuser hasn't reached temperature — print a throwaway page first.
Does Your Printer Have a Built-In Cleaning Page?
Many laser printers can run a cleaning page that pulls a sheet through the fuser to remove stuck toner. On many HP LaserJets it's under Setup > Service > Cleaning Page (or in the embedded web server); Brother and others list cleaning routines in the maintenance section of the manual. It's worth running before you replace parts.
Fix It in This Order
- Print a test page and identify the streak type.
- Turn off toner save and check the paper type setting.
- Rock the toner cartridge and clean the corona wire.
- Remove debris; run the printer's cleaning page.
- Swap the toner cartridge.
- Swap the drum unit (or the toner-and-drum combo on HP and Canon printers where the drum is built into the cartridge).
- Replace the fuser, or call for service if streaks persist.
Frequently Asked Questions
Can a new toner cartridge cause streaks?
Yes, occasionally — a shipping seal left in place, a damaged wiper blade or toner that settled in transit can cause streaks. Rock the cartridge, make sure all protective tape is removed, and reinstall. If streaks continue, ask the seller for a replacement. Castle Ink toner is covered by a 100% satisfaction guarantee.
How do I know if it's the toner or the drum?
Swap one at a time. If a different toner cartridge fixes it, the old toner was faulty. If not, the drum is the likely cause. On HP and Canon printers where the drum is inside the toner cartridge, a new cartridge replaces both.
Can I clean a laser printer drum?
Only very gently, with a dry, lint-free cloth, and only to remove a visible speck. Scratches and wear can't be cleaned away.
How do I clean up spilled toner?
Wipe it up with a dry cloth or use a toner vacuum. Don't use a household vacuum — the fine powder passes through the filter and can damage the motor. On skin or clothing, use cold water; hot water sets toner.
Why does my laser printer print a black page?
An all-black page usually means the drum isn't being charged — a failed drum, a damaged charge roller or a bad contact. Try a different drum unit first.
Why are there streaks after my laser printer sat unused?
Toner settles and can clump. Rock the cartridge gently and print a few pages; the streaks usually clear.
Do compatible toner cartridges cause streaks?
A quality compatible cartridge should print cleanly. Problems usually come from very cheap, poorly refilled cartridges. Learn the difference in compatible vs remanufactured vs OEM.
Keep Printing
If the fix is a new part, Castle Ink has you covered: Brother toner, HP toner, Canon toner, Xerox toner, Brother drum units and HP and Xerox drum units. Look up your model on the Find Ink by Printer page (toner and drum guides are listed there too), or visit the printer troubleshooting center.
Handy for cleaning: lint-free microfiber cloths and disposable nitrile gloves.
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