No matter what type of laser printer you own, you need to keep a close eye on print quality. The quality of the pages emerging from the printer can tell you a great deal about the condition of the printer. The sudden appearance of black toner marks or toner dust on the printouts is cause for concern; you need to find the source of the problem as soon as possible.
Leaking Toner Cartridge
When black toner dust and spots appear on the paper, the most likely culprit is a leaky toner cartridge. If the toner dust started appearing around the time you changed the cartridge, you can be fairly certain that is the problem. Even if the toner cartridge has been in service for some time, it can still spring a leak. Remove the toner cartridge and sit it on a white cloth or paper towel. Allow it to sit for a few minutes, then pick it up and look for toner residue. If the cartridge is leaking, it should be replaced at once--a leaking toner cartridge can cause problems in the entire printer.
Dirty Printer Path
Even when the cartridge does not leak, some loose toner may get into the printer and cause black streaks and spots on the paper. When this happens the printer path needs to be cleaned thoroughly. To start the cleaning process, first remove the toner cartridge and set it aside. Then use a small computer vacuum and a soft cloth to clean the interior of the printer. If black spots are still appearing on the printouts, purchase a pack of printer cleaning sheets at an office-supply store and run these sheets through the printer until there is no more toner residue. Printer cleaning sheets have a slightly sticky surface that attracts loose toner, paper dust and other contaminants and leaves the printer path clean.
The job of the fuser is to "fuse" the ink in the toner cartridge to the paper. If the fuser is worn out or not working properly, the ink will not adhere properly to the paper, resulting in black marks, streaks and ink that rubs off the paper easily. To check for this problem, take a freshly printed page off the printer and rub it vigorously. If the print rubs off the paper, the most likely problem is a failed fuser cartridge. You can order a new fuser from an office-supply store and install it yourself using the instructions included with the new cartridge.