HP printers are an enigma, I've had 4 so far...in each case it was printhead problems that could not be solved. In 2 cases the black refused to print, while on my current model everything on photograph printing is coming out with a green tinge. You can buy cleaning cartridges but I've tried these and no joy. HP customer service takes ages to contact, and if the machine isn't fairly new they don't want to know, and no-one locally ever does refurbishment.
So, try the cleaning cartirdges, put it through all the print clean options on the menu, and if it doesn't improve chuck the whole thing away. The choice of domestic printers is huge, but they all have problems and/or expensive inks.
Steve Riches., September 2009