Full channel dropout after cleaning adjacent channel in 7900

My 7900 (running a K5 Cool/K4 Warm Piezo Pro setup) has developed a troubling nozzle drop-out pattern. I’ve been printing on this 7900 (and also a P9000) for quite a while and I’m pretty familiar with EPSON nozzle failure symptoms and causes but this one has me stumped.

First, all the symptoms are on carts/channels in the LEFT ink bay. Here’s a typical scenario:

  1. Fire up printer to start a printing session
  2. Run nozzle check - missing one or two adjacent nozzles on bottom row of Orange channel, and one nozzle on bottom row of Yellow channel. Everything else is good except for delaminated Green and K channels which I’ve mapped out.
  3. Reboot printer into Service Mode, run CL1 pair clean on Y/LLK nozzle pair, run CL1 pair clean on OR/GR nozzle pair.
  4. Run nozzle check - Orange channel has completely dropped out

At this point, it takes several more cleanings and perhaps a CL2 or CL3 to get the Orange channel back. I have also seen a few cases where the Orange channel is completely gone after doing a print; i.e. all nozzles were good when the print was started, but a nozzle check after the print shows Orange completely missing.

It’s not clear to me what is causing this. Could it be:
a. Bad LEFT ink bay? I mention this since it seems it is always the adjacent Orange that drops out when I clean the Yellow.
b. Ink starvation?
c. Damper issue? The Ink Selector was last replaced in July 2014. I realize the Ink Selector should be replaced about every 2-3 years, but I haven’t been using this printer heavily.
d. Cleaning station issue? Pump/cap assembly was replacedin January 2017 when I converted printer to PiezoPro ink

Because of two delaminated channels already (Green and K) I’m evaluating whether it will be cost-effective to fix this dropout issue.

Any ideas what is most-likely causing this dropout behavior?
Thanks.

So the orange is part of the green/orange channel pair. Because green is de-laminated, the orange channel shares the same “lamination pad”. While I don’t think it’s exactly de-lam that is causing the issue, the orange certainly will be the next one to go.

What I think is actually happening though is a combo where the cleaning unit is not making good contact w/ the head and the damper is dropping full air into the channel every once and a while. This can cause the full channel drop + clean + recover thing. I’ve seen it and replace of the ink selector (dampers) and cleaning unit generally fixes it. There is a cleaning unit adjustment in maintenance mode as well which changes the contact pressure of the cleaning unit agains the head (miss-aligned cleaning unit is a main cause of de-lamination by the way).

-Walker