DIAGNOSIS This is uneven toner distribution, almost always caused by a failing imaging unit (drum) or poor electrical contact, not the toner cartridge itself.
FIX Reseat the imaging unit and toner cartridge together to re-establish electrical contacts.
- Open the front cover.
- Remove the toner cartridge, then remove the green imaging unit (drum) behind it.
- Gently wipe the long, skinny electrical contact strip on the back of the imaging unit with a dry cloth.
- Reinsert the imaging unit firmly, then the toner cartridge. Close the cover and run a test print.
IF THAT DIDN'T WORK The imaging unit is worn out and needs replacement. It's a consumable part (Canon NPG-83) with a lifespan separate from the toner. Replace it.
HEADS UP Using paper that's too humid or textured can accelerate drum wear and cause this symptom. Store paper in a dry place.