Why it stoped using black ink for printing?
My HP photosmart C4780 printer will not print the black ink. I have replaced the black ink cartridge twice (original HP 60XL cartriges) and have had the same issue each time. The color is printing fine but no black. I have tried 'calibrating' (alignning) them after I put them inside but it won't even print the black ink on the calibration page. I did automatic printer head cleaning 4 steps it does not help. What do I do?