I did a self test on a 4800 and found some clogging issues on the black cartridge. After several self test attempts, the message ‘nozzle still clogged’ came up. So, I did a power clean, after completion of cleaning, it prints nothing in a self test even though the head is moving. I did a power recycle with no change; the message ‘nozzle still clogged’ came up after printing several blank sheets.
This is because you have (most likely) old dampers that are filled with crud and need to be replaced.
Or you have a plugged tube from the flush box to your ink vacuum that is not allowing the cleaning assembly to suck ink.
You need to clean out the cleaning assembly (cap/flush unit) first and do another normal cleaning. If no nozzles still you need to replace you dampers.
If you are using refillable cartridges, make sure the vent holes are open.
Thank you very much for your assistance.