Why does a new cartridge not fix the line on my page?

Because the line was probably never the cartridge. A sharp vertical line in the same position on every page usually means a scratched drum or a nicked wiper blade, and if the drum is a separate unit from the toner — as it is on many Canon and Brother machines — a new toner cartridge changes nothing. Smudging and ghosting point at the fuser, which is part of the printer rather than the cartridge.

What is the difference between a streak and a band?

A streak runs along the direction the paper travels, so it appears as a vertical line on a portrait page and is caused by something touching the same spot on every sheet. A band runs across the page and repeats at a fixed interval, which points at a rotating part — the interval tells you which one.

Can print-quality problems be caused by the paper?

Yes, more often than people expect in Delhi. Paper that has absorbed humidity feeds unevenly and holds toner differently, which shows up as patchy density and curl rather than sharp lines. If quality drops in the monsoon and recovers later, try a freshly opened ream before assuming the machine is at fault.

Is it worth cleaning inside the printer myself?

Loose toner dust on accessible surfaces can be wiped with a dry lint-free cloth once the machine is off and cool. What is not worth attempting is anything involving the drum surface, the laser optics or the fuser assembly. Those are easy to damage permanently and they are the parts a cleaning attempt most often makes worse.

Streaks, Lines and Ghosting: What Each Means

A printer printing lines on paper is not a vague fault. Each pattern comes from a specific component, and the page in your hand is a diagnostic readout — you just have to know how to read it.

This is a guide to doing that. Work out which pattern you have, and you will know whether you are looking at a cartridge, a fuser, or something that needs a technician, before spending anything.

If you open the machine: power it off and let it cool first. The fuser reaches temperatures that will burn you and stays hot after the printer stops. If a step needs force or reaching past a moving part, stop there.

A printer printing lines on paper: start with direction

Hold the page in the orientation it came out of the printer. There are only two possibilities, and they have completely different causes.

Along the direction of travel — a vertical line down a portrait page. Every sheet passes the same point on some component, so the defect is continuous. Something is touching, scratching or blocking in one fixed position.

Across the direction of travel — a mark that repeats down the page at a regular interval. This is a rotating part, marking the page once per rotation.

That distinction alone eliminates half the possible causes.

Vertical defects

A sharp dark line, same position, every page

The most common single complaint. It usually means the drum surface has been scratched, or the wiper blade that cleans the drum has a nick in it and is leaving a track of toner behind.

Neither is fixed by adding toner. If your machine has an all-in-one cartridge with the drum built in, the cartridge is finished. If the drum is a separate unit — common on Canon and Brother — then the drum is the part to replace and a new toner cartridge would have been wasted money.

A white streak, same position, every page

Toner is not reaching the paper along that line. Either the cartridge is low and the toner has not distributed evenly, or something is physically blocking the path — debris on the developer roller, or a piece of paper fragment lodged after a jam.

Take the cartridge out and rock it gently end to end. If the streak fills in, the cartridge is running low. If it does not, look for debris.

A broad vertical smear or repeated dark band

Usually contamination on the transfer roller, or toner that has escaped inside the machine and is being picked up. Machines in dusty environments reach this sooner, which is why sites like workshops and dispatch bays need cleaning on a schedule rather than on failure.

Defects that repeat down the page

This is where a ruler earns its keep, and it is the technique most people have never been shown.

A rotating component marks the page once per revolution. The distance between two identical marks equals the circumference of whatever is causing it. Measure that gap accurately, and the service documentation for your model will tell you which roller has that circumference.

You do not need to memorise any numbers. What matters is the method:

Print a page with the defect clearly visible — a light grey fill works well.
Find two consecutive identical marks.
Measure between the same edge of each, in millimetres.
That measurement identifies the component.

A shorter repeat generally points at a smaller roller such as the charge or developer roller. A longer one points at the drum. A repeat that appears only after the page has been through the fuser points there. Telling a technician "the defect repeats every 40 mm" turns an hour of investigation into a part order — it is the single most useful thing you can put in an email about print quality.

Ghosting

Ghosting is a faint copy of something printed higher on the same page, reappearing further down. It is distinctive once you have seen it.

It happens when the drum does not fully discharge between one image and the next, so a residue of the previous image is still present on the next rotation. Cold conditions make it worse, which is why some offices see it first thing on winter mornings and not at all by afternoon. Low-quality or wrong-specification toner is the other common cause, because the powder's electrical behaviour is part of what makes the discharge work.

If ghosting appeared after a change of cartridge supplier, the cartridge is the first thing to suspect.

Toner that rubs off

Print a page, rub the black areas firmly with a finger, and see whether it smudges.

If it does, the fuser is not reaching temperature. The image formed correctly and was placed correctly; it simply was never bonded to the paper. No cartridge change will fix this, and continuing to print in this state means every document you produce can be smeared by a thumb.

This is a printer repair rather than a consumable, and on a machine that has printed steadily for years it is a wear part reaching the end of its life rather than a surprise failure.

Grey background across the whole page

The page has a light overall haze rather than clean white. Usually the charge roller failing to hold the drum at the right potential, or toner that does not match the machine's specification.

Worth knowing: this is one of the clearest symptoms of poor-quality toner. If it started after switching supplier, that is your answer, and it is the reason how a cartridge is refilled matters as much as whether it is refilled.

Reading it back

What you see	Most likely cause
Sharp vertical dark line, every page	Scratched drum or nicked wiper blade
Vertical white streak	Low toner, or debris on the developer roller
Marks repeating at a fixed interval	A rotating roller — measure the interval
Faint repeat of an earlier image	Drum not discharging, or wrong toner
Toner smudges when rubbed	Fuser not reaching temperature
Grey haze over the whole page	Charge roller, or poor-quality toner
Patchy density, curled paper	Humidity in the paper, not the machine

Photographing a defect so it is actually useful

Most print-quality conversations start with a description, and descriptions of visual defects are unreliable. A photograph is better, and a good one turns a diagnostic visit into a repair visit.

Photograph the page flat, in daylight, from directly above. Angled shots distort the spacing between repeating marks, which is the measurement that identifies the roller.

Include a ruler along the defect if it repeats. That single addition lets whoever reads it measure the interval without having the sheet in hand.

Send the whole page, not a crop. Where a defect sits relative to the leading edge matters — a mark that always appears the same distance from the top is telling you something a crop hides.

Print a page of even grey first. Defects invisible on text are obvious on a mid-grey fill, because you are looking at the machine's behaviour rather than at your document.

Keep the physical sheet. Photographs are for triage; the sheet is what gets measured. If the fault turns out to be a consumable someone else supplied, it is also the evidence.

Before you spend anything

Two habits save the most money here.

Keep the bad page. A photograph of a defect is worth more than any description, and the physical sheet is better still because the repeat interval can be measured from it.

Do not buy a cartridge to test a theory. For fuser faults, drum wear on separate-drum machines, and charge roller problems, a new cartridge changes nothing at all. Work out which pattern you have first — and if it points at the machine rather than the consumable, that is a repair, not a purchase.