Such as: HP 540, 660, 682, 693, Epson 640, 660, 800, 850, Canon BJC 240, 4100, 4300, etc.

Problem: Epson 640/660 Print quality problems
Diagnosis: Colors missing, faded, or jagged
Solution: Recharge ink/Clean print heads
Process: Hold down ink button (the lower of the two buttons) for about 5 seconds; printer should make some noise as it goes through the process of cleaning the ink heads. Try printing again to see if that fixed the problem; if it didn't then try again up to three times before sending in a maintenance request. Also, check to make sure that the paper is being fed into the printer correctly; paper that isn't quite snug against the sides of the paper-guides can end up with a blurry, jagged appearance.

Problem: Missing color.
Diagnosis: One of the color reservoirs in the color ink cartridge has been depleted.
Solution: Replace the cartridge.
Recommendation: If possible, avoid assigning projects to the class that rely heavily on one color. This may be difficult, especially around holidays, but if you are sensitive to what colors are being used and how much, you can get more life out of the cartridge.

Problem: Lines running through the page.
Diagnosis: Dirty print head.
Solution: Most of the printers have a software-based print-head cleaning utility. For instance, the HP printers will generally have an entry in the Windows Programs menu, usually labeled Utilities. You should also be able to access these features via the Printers menu, by going to the Start button, choosing Settings, then Printers, then selecting the printer you are having trouble with. To select a particular printer, right click on it and choose Properties from the pop-up menu. In the Properties window, there will usually be a Utilities or Control tab. Bear in mind that the method for getting to print head cleaning utility will vary depending on the printer.