Fault diagnosis
Spots and marks that are not in a line.
Scattered dots are a different fault from streaks. If they repeat at a regular interval they are a roller; if they are genuinely random, they are contamination.
Toner spots come from loose toner escaping where it should not. The usual sources are an overfull waste chamber, a cartridge that has been over-filled or leaks, contamination on a roller, or paper dust building up in the path. If the spots repeat at a fixed spacing down the page they are coming from a roller; if they are random, something is loose inside.
First: regular or random?
Hold the page up and look at the spacing.
- Repeating at a consistent interval — a rotating part. Measure the gap; see lines and streaks for the method.
- Scattered with no pattern — loose toner or debris in the paper path.
- Only along one edge — usually a leaking cartridge or a contaminated feed roller.
- Only on the reverse — the paper path itself is dirty, not the imaging system.
Random spots
Overfull waste chamber
Spent toner collects in a chamber inside the cartridge. When it fills it packs and starts escaping, dropping onto pages. This is the most common cause, and it is exactly what a proper refill empties and a drill-and-fill refill does not.
Over-filled cartridge
Too much toner leaks past the seals. Another sign of a poorly done refill.
Paper dust
Paper sheds fibre and filler, which accumulates on rollers and in corners. Cheap or recycled stock sheds more. Eventually it comes off onto pages.
Something spilt inside
Toner from a previous leak, or debris that came in with the paper. Usually clears with a proper clean.
Marks on the back of the page
Almost always a contaminated pressure roller or a dirty duplex path. Very common after a cartridge has leaked and the machine has not been cleaned out afterwards.
What you can do
- Print ten blank pages — sometimes loose toner clears itself out
- Take the cartridge out and check for toner around the seals
- Look for spilt toner in the cavity. If there is a lot, stop and call — vacuuming it with a normal vacuum makes it worse and can be hazardous
- Try a fresh ream; cheap paper sheds badly
If the cartridge is visibly leaking, take it out and stop printing. Toner circulating through the machine gets onto the fuser, and then you have two faults instead of one.
Common questions
What causes toner spots on printed pages?
Loose toner escaping — most often an overfull waste chamber inside the cartridge, an over-filled cartridge leaking past its seals, or contamination on a roller.
Why are there marks on the back of my pages?
The paper path is dirty rather than the imaging system — usually a contaminated pressure roller or duplex path, often after a cartridge has leaked.
Can I vacuum toner out of the printer?
Not with a normal vacuum. Toner particles are fine enough to pass straight through the filter and back into the air. It needs the right equipment.
The spots appeared right after a refill.
Over-filling or a waste chamber that was never emptied. Both are refill-quality problems and both are fixable — bring the cartridge in.
Tell us what it is doing.
Call and describe the make and the symptom — most jobs are done in a single visit, and we will tell you straight if it is not worth repairing.