i've done all the recommended steps. here's a rundown:
had a light cyan clog some months back, quickly fixed with nozzle clean.
i live in very low humidity and was printing about 1/week. did not know at the time that leaving the machine on was a bad idea.
about 10 days after a good print, i suddenly had 4 channels blocked. 3-4 cleanings had all but matte black opened up. this is when i learned many multiple cleanings are a bad idea as the heat in the print head can gum things up even worse.
cleaned capping station and wiper with windex.
scrubbed print head with windex.
was advised there are 2 options: use initial fill cycle with piezo flush or attempt purging single nozzle (was told the latter is difficult, unlikely resolution).
purchased 9 refill carts, pzflsh, and syringe. then learned the software to do the flush is $20 and only works on windows. i'm on osx mavericks.
continued my scavenger hunt and found quad tone rip, for $50, was necessary to do single channel purge.
downloaded the purge target photoshop file and edited it to have a single bar of matte black covering the whole page.
printed in qtr calibration mode with ink at 100%, 2880dpi and piezoflush loaded in the chamber.
15 pages later, not one drop on the paper, but somehow my cartridge is now only 1/3 full. yes, i removed the breather plug.
i don't know what else to do besides the flush kit. after reading here, i have no confidence that using the initial fill/flush trick will do anything but waste ink from all the good channels even if i find a pc laptop to hook up to.