I have a problem printing yellow and the cyan yellow (E nozzle check). Have installed two printheads new one and a replacement from canon. New cartridges, cleaned contacts, not plugged, no error lights, but it still will not print the yellow and the cyan yellow (E on nozzle check). Canon says it could be something else. Does anyone have any idea what might be causing this? Eprom print out indicates service error 5100. Got it to print yellow but not the E nozzle check