Ink Drop Out of PK and LK 4900

After power cleaning, I get a full nozzle check. Both PK and LK drop out, mostly LK, during printing. I put in a new damper assembly and I have new ink lines I can install. I tried to flush the lines with Piezo-flush but it still happens. Could it be a bad ink cartridge holder? Any advise before I get even deeper into repairs. This is a Epson 4900 about 5 years old

Did you make sure to remove the orange vent plugs on your refillable cartridges after install as per the instructions?

best regards,

Walker

I invested in OEM Epson carts just in case; same results. And yes the orange plug was removed. I wonder if cart holder is letting in air or is plugged or just malfunctioning? I read somewhere that “drop-out” is air in the lines.
Thanks for reply, Chris