What does the nozzle check test look like? If the usual nozzle check test looks OK, then enter the self diagnosis mode and do a nozzle check test there. It will give you a better look at what is going on. Does it do this for every color or just for black? My 1204 has done something similar to this. It cleared up when I removed the left-side cover and cleaned the encoder disk. It would be a good move to also clean the long encoder strip on top of the printer, too.