A dirty cartridge most likely causes lines in your print. Run the Clean Cartridge test described in the manual and check to see that there are no breaks in the diagonal line on any of the colors. If the problem continues, you can run the clean cartridge more than once. Also remove cartridge and clean off bottom with a tissue. If cartridge does not come clean then it is a defective cartridge and must be replaced. Another possibility is bad data. Be sure that you're parallel port is set to ECP (see "Q: Why is the printer not responding from the Print Command?") For best results we recommend a direct connection from the parallel port to the printer with a IEEE certified cable that is 6 feet (2 m) or less in length.