My printer, HP OfficeJet Pro 6960, won't print print in black. I have tried: cleaning printhead, cleaning cartridges, Googling topic and following suggestions, removing and reinstalling printer and more. Nothing helps.
Would be grateful for any proven suggestions. (I just paid more than $140 for a set of new cartridges, thinking the problem was that older cartridges were empty.)
Thank you very much.
