Canon Pro-10S, Cyan is printing in my Chroma Optimizer (CO) on the nozzle check test pattern. Can someone explain what the problem is?

[palombian]

I would not exaggerate with cleaning solutions, ammonia is a measure of last resort.
Long soaking in inoffensive products (as a drop of dish washing liquid in a bottom of deminaralized water) is often the best solution.
Once you see improvement in the cyan, a few nozzle checks every day keeps the ink running and chances are the last clogs will dissolve.
Good luck (and patience) !

 

[The Hat]

I could not see any C in the CO.

Just looking at your latest nozzle check.. it still doesn’t seem right to me.. CO bubbly..

You never said what type of ink your using in your cartridges, that can make all the difference here..

 

[palombian]

Just looking at your latest nozzle check.. it still doesn’t seem right to me..

You never said what type of ink your using in your cartridges, that can make all the difference here..

Indeed, the cyan is far from OK, but with good ink maybe recoverable.

I've always been extremely paranoiac on the nozzle checks, inspecting them with a magnifying glass.
You must see every dot !

PS: I don't know where you are located, but I never had any problem with octoinkjet.co.uk cyan (or the one from precisioncolors.com in the US).
You can also refill with large format inks, a PFI-106 costs about €70 for 130ml, that's half price of PGI-72 14ml carts. Good for at least 10 refills.
Cyan is no problem, but it is another ink set, not all colours match so you need custom profiles.