Officejet Pro 6978 not printing cyan even though test page from printhead cleaning looks good.

[Aislin2476]

I have an Officejet Pro 6978 with Instant Ink, and it has not printed cyan well since the cyan ink recall of a year or so ago.  At that time, one of my cartridges in the printer was a recalled one, and although I replaced it as soon as I was notified, the cyan hasn't worked well since.   I've run the printhead cleaner (3x, waited 30 minutes and run it 3x again), tried doing a hard reset by unplugging the printer from both ends for 30 minutes and plugging it straight into the wall, changed ink cartridges, made sure the orange tabs were trimmed flush with the cartridge, reinstalled the driver, and everything else I've ever seen mentioned on here.

The problem is that cyan looks fine on the test pages after I do the printhead cleaning, but then when I try to print an image in color, the cyan looks good on the top 1/3 of the page and then gets all streaky.  I think the printhead cannot be replaced on this model, correct?  I'm not sure what else to do to try to fix the darn thing.  I have a buttload of instant ink cartridges backed up, and the new printers that will do instant ink either look very expensive or very crappy.  This one was about $120 when I bought it and has every function I need.  I really don't want to have to replace it.