The nozzle check was perfect before refilling the inks.
I'll answer your other questions in point form.
1) Was the cyan printing well prior to refilling the carts?
2) Generally, how often does this printer get used, vs. how long does it sit unused?
A) I haven't been very productive lately.
Weekly, I run a head cleaning and agitate the cartridges (and my reserve inks) and print a 24x36 poster.
3) Are any nozzles printing in the C position of your nozzle check, or if the entire position blank? If some nozzles are printing, about how many nozzles, or what percentage of the position is missing?
A) Consistently, 3-4 lines are blank (always the same two about 3/5 of the way down the cyan pattern).
All other colours are perfect.
UPDATE Sept 28: After printing cyan sheets until the cleaner was flushed from the line, I ran a nozzle check, much worse, now about 50% gone, oh dear!
UPDATE 2, Sept 28: Ran 2, paired power cleanings, now only about 30% of C missing. Subsequent normal paired cleanse, no improvement.
UPDATE 3, Oct 2: Now down to about 20% missing on C
4) What are the humidity and temperature levels in your printing environment?
A) Temp about 65-75, but for a few hot summer days, humidity not controlled (heated by radiators)
5) Have you already tried cleaning the printer's capping station, wiper blade and bottom of the print head?
6) Have you done any power clean cycles?
A) Yes, many paired power cleans to charges the cyan with cleaner, then more power cleans and prints of cyan pages.
By the way, I still can't locate that inkseparation8.tif.
7) Are you printing from Mac or PC?
Also, I went to 2manuals.com and downloaded the 7900 Service Manual (mistake eh?), returned to to get the "Epson 7900 Field Repair Guide," none to be found. Any other sources? Do you know of a video for capping station, head etc. maintenance on a "pro" printer?
Thanks for your attention to this matter.
All the best,