Sorry I can't be of any help, but I found it interesting how you discuss the nozzle check from the service mode. I started a thread about this exact same thing almost a week ago and I was surprised that nobody replied.
http://www.luminous-landscape.com/forum/index.php?topic=92917.0
Because the iPF printers automap the blocked nozzles, its hard to know how healthy your printhead really is. After years of owning my printer, I was surprised that I hadn't run across this ability in service mode. One day the printer just worked, next day it says the printhead needed replacing and I found this frustrating because there really was no warning. I do wish Canon would say how many nozzles can in fact be blocked and hence remapped and of course also how close you are to using up all the remapping ability.
At any rate, if you have time, can you post a picture of your TRUE nozzle pattern from the service mode? I only see an issue with my blue channel, it seems like there are lots of missing nozzles in the red outlined area, but perhaps "lots" is quite subjective and so I'm curious about what other people get from their true nozzle patterns.
Here is a picture of the true nozzle pattern in service mode of my iPF8410:
https://dl.dropboxusercontent.com/u/15547362/CanoniPF-servicemodenozzlecheck.jpgThis might be useful for you, the
Canon iPF troubleshooting Guide Level 2 document.
Look at Page 4-2. It might help you diagnose your problems:
Here is an actual printout from my printer, one right after the other. Suddenly many colors and matte black go missing. The most obvious is the missing matte black. It is a total disaster. This replacement printer is no more than a month old and has made less than 20 sq ft of prints. I am thinking - aren't these the kind of problems that Epson printers face, NOT Canon?!?
These machines are useless pieces of junk. If anyone want to buy a large format printer today for ultra high end photo printing, you basically have these three options:
1. HP Z3200 which is just a dinosaur. No more new printers are coming from them. The paper loading design is a disaster and the screening is terrible.
2. Epson 9900. Good luck with that. Enough said.
3. Canon iPF8400. Electrical problems, failing heads, crazy weird ink dropouts and disappearing gamuts. Add to that the possibility of the worst customer service you will ever face and things look grim.
