i had kind of the same problem, but with an HP printer. i got it back to almost-good quality (as in, as good as it was before, w/o any streaks in the black ink) several hours ago by a) cleaning the gold contact dots and the nozzles of the CARTIRDGES with a q-tip, and then b) cleaning the gold contact dots on the print CARRIAGE as well, then i used the hp software to clean the cartridges, three times in a row. a full page b+w doc now only has 2 or so streaks, while colour pics are ok too. however, im still going to call hp about, because it used to print everything perfectyl...
please wriute back if this works...