Laserski tiskalnik

Symptom: horizontal streaks on the page. If you see a regular horizontal line on your output, it's probably caused by an irregularity in one of the many rollers that the paper must pass by on its journey from the paper cartridge to the output bin.

To identify the roller, you'll need to measure the distance between the lines. If the horizontal lines are always spaced the same distance apart, then that distance is the circumference of the bad roller.

Use the following numbers as a handy-dandy key. Just measure the distance between the regular horizontal lines with a ruler, and then read off the name of the bad roller. Whether or not you want to try to replace the problem child is up to you; getting to some of those rollers is a bit hairy. In my experience, however, the most common distance is 3.75 inches: the circumference of the photosensitive drum.