For some reason my Epson Stylus 600 stopped printing using the black ink (colour cartridge prints fine). I thought the cartridge was empty (but did not perform the ink level check), so I replaced it with a new one, but the printer still will not print using the black ink. When I try to print a letter, the printer goes through the motions, but the page comes out with olny a few faint black lines here and there. I think it's a blockage but after performing the nozel cleaning and print head cleaning using the cleaning utility, I still have had no luck. What do I do now ?