The fuser in a laser printer does what it sounds like it would do: it fuses ink from the toner cartridge onto paper.
The fuser assembly has two rollers: a heating roller and a pressure roller. One roller heats up the toner, from the toner cartridge, and the other roller applies pressure to the melted toner, fusing it with the paper to create printed output.
There's no denying it. Laser printers are work horses.
But constant wear, caused by small particles of dust, paper, and toner, make the fuser mechanism one of the most common parts of a laser printer to fail. Wear and tear of the printer fuser often shows up as verticle lines on your printed output. The lines are made by scratches on the rollers, caused by the accumulated dust particles.
The heating element in the printer fuser can also fail. A laser printer fuser uses a quartz bulb to apply heat to the roller, and the bulb will eventually burn out. When this happens, your laser printer will often show an error or service code indicating that the printer fuser assembly needs to be replaced.
Other printer fuser problem areas incude, the power supply and the feed and transfer rollers. Many laser printer manufacturers offer fuser assembly maintenance kits, sometimes called a laser printer maintenance kit, with spare parts to replace the worn ones.