How to fix lines when copying or scanning from the document feeder

One of the most common problems on a copier, printer or scanner is lines on the output. There are various reasons for lines to appear, and by narrowing down the potential sources of the problem you can usually figure out a way to fix it. For example, if the lines don't go all the way to the edge of the page (stopping a fraction of an inch away) then the problem most likely lies with the machine's optics/scanning section, rather than any of the printing components.

If the lines appear when you are copying or scanning from the document feeder, but not when you place the original on the glass, then the problem is most likely dirt on the slit glass. The slit glass is the small strip of glass located next to the larger platen glass. Depending on your copier model, the slit glass may be located to the left or right of the platen glass.

For most copiers, you can clean the slit glass with alcohol and a lint-free rag, but check your device's manual first. If alcohol cannot be used, a dry lint-free rag will often remove the offending dirt. The slit glass gets dirty easily -- from paper dust, other dust in the air, or (not uncommonly) correction fluid (i.e. Wite-Out).

More often than not, cleaning the slit glass will remove the lines. (It may take a couple of passes with the rag.) If after cleaning the slit glass the lines remain, there are two likely sources of the problem:

• The underside of the slit glass (the side you can't get to without removing the glass) is dirty.
• There is dust on one of the mirrors, or somewhere else in the optics section.

For either of those problems, it's recommended to call a trained service technician. Exposing or adjusting the optics section can cause other issues.