Bubble air in the feed tube Epson R3000

[Ellepi]

I have an R3000 printer, after two years of not using matte black, I switched from photo black to matte black and the black nozzles stopped working completely.
I did a few cleaning cycles but nothing has changed.
So I tried to clean the print head by injecting a cleaning liquid into the black ink tube.
But this has introduced air bubbles into the tube which no longer go away and the black nozzles continue to be blocked.
Anyone know a way to get the air bubbles out of the tube?
The printer is still in perfect condition and printed great with black photo ink before attempting to clean, I would like to avoid having to throw it away.
If anyone can help me thank you so much.

 

[Ink stained Fingers]

I have an R3000 printer, after two years of not using matte black, I switched from photo black to matte black and the black nozzles stopped working completely.

I'm afraid that the matte pigment ink created a sediment in the resp. tube, and that stuff got pressed into the ink switch and into the nozzles once you switched over to the matte black ink. I'm not using a R3000 so I regret that I can't tell where and how to clean the affected parts - tubing - switch - nozzles but I'm afraid that it won't be that easy.
I heard from other users of an R3000 or P600 that they rather use a 2nd glossy black cartridge , fill it up with matte black ink, swap the cartridge and print a few black pages to replace the ink in the tube - without triggering the ink switch at all via the paper/ink selection in the driver.