I have a number of samsung printers that all have the same issue. When printing, the document produced always has a faint ink mark running down the length of the page, indicating that ink remains on the rollers. I've taken each printer apart, given them a clean, even changed the toner incase that was the issue, but the problem remains. Does anyone know of an effective way to clean printers with this problem? Is there some kind of special paper that you can print on which cleans them, in a similar way to the way tape deck cleaners use to work?