CJV30 160 Replaced almost everything and yellow does not print

Hi all, I usually find the solution on this forum but I could not this time. I hope someone can help me.
I replaced the main PCB/main board, replaced the print head, replaced the ink slider board and all the flex cables on the printer(Mimaki CJV30-160), installed a new capping station and new dampers and all are filling up with ink, there is no air bubbles in the lines. When I did a print test both yellow did not print at all, not even a speck of ink. All other colors are fine. I removed and re attached all the flex cables cables. I also noticed that on the capping station the yellow is not present when I do an ink fill. Did Nozzle wash over 90 minutes, like 15 hard cleaning, I tried everything I learned on this forum but now I am really lost. I have absolutely no idea what the problem is. Does anyone have an idea of what can be the problem?

 

Solventinkjet, thank you so much for your advise. I did exactly what you suggested and indeed the yellow was printing throught the black nozzles. I figured it must be that the yellow nozzles must be clogged. I used a siringe with distilled water hooked it on the ink manifold nipple of the yellows and it appeared to be clogged. I pumped with very litlle pressure for about 30 minutes untill some of the water started to drip from the yellow nozzles. I did notice that there was a thick sticky substance that appeared to be some type of grease comming out of the nozzles but I am not sure what is was . Took my time and I basically spent all afternoon slowly pumping distilled water throught the 2 yellow ink nipples on the ink manifold untill it started running clear. Did a couple of empty siringe pumps untill only air came out of the nozzles. Did a fill ink, soft clean and a test print and it started to print from both yellow. The print head was a brand new original Epson dx5 installed straight from the box and never had any ink in it. I am happy that my problem is solved. I can finally start printing again.