I put my 4900 aside for five months, filled with flush, but I forgot to do a black ink swap. After filling it with ink again and making some prints I did do a black swap, the black channel faded and after a while I got a completely blank nozzle check. Filled the printer with flush again, did an initial fill and got a partial nozzle pattern, then nothing, then a full pattern, finally nothing again. The stupid thing is that I overlooked that orange (filled with flush) ran out of flush. I now get a completely blank nozzle pattern there as well, even after some initial fills and checking that the cart was primed.
Is there a chance that a new pump unit and a new ink selector will bring back the black?
Any suggestions what to do to get back the orange channel?
I know I still have enough channels for K7, but I would like to keep the option to switch to colour, if possible.