Why Is My Printer Printing Lines?

Lines on laser prints follow rules. The direction of the line, whether it repeats, and how far apart the repeats are will identify the failing part with surprising precision — technicians literally measure the gap between repeating marks to know which roller to replace.

Vertical lines (running the direction the paper travels)

• A thin, dark, dead-straight line in the same spot on every page — a scratch on the drum or a nick in the cleaning blade. If your model's drum is built into the toner cartridge, a cartridge swap fixes it; if the drum is a separate unit, that's the part.
• A white or faded stripe — toner starved in that stripe: low/clogged cartridge, or debris in the laser path. Rock the cartridge, then swap a known-good one to confirm.
• Lines only on copies, not prints — dirty ADF scan strip on the scanner, not the print engine at all. Clean the narrow glass strip beside the main scanner glass.

Horizontal lines and repeating marks

A mark or band that repeats down the page at a regular interval is a rotating part stamping the page once per revolution. The repeat distance is the part's circumference — roughly:

• Repeats every 3–4 inches — usually the drum.
• Repeats every 2–3 inches — usually a fuser roller.
• Repeats every 1.5–2 inches — often the transfer or developer roller.

Exact intervals vary by model, but the principle holds: measure the gap with a ruler and write it down. That one number, plus your model number, usually identifies the part before anyone opens the machine.

What to do about it

1. Swap the toner cartridge first — on cartridge-integrated-drum models this eliminates the most common culprit in one move.
2. Run a cleaning page to clear toner buildup that can mimic a failing roller.
3. If the line survives both, the wear is in a roller, the fuser, or the drum unit — parts-level work. A repeating mark that's getting darker week over week will not improve on its own, and a damaged fuser roller can eventually mark every page the machine prints.