Hello all....I'm having unresolvable banding on my 6300, and I hope someone may have an idea that I've not already tried. Long story, but here goes...
The printer started banding in November 2012; it turned out to be a failed R printhead and replacing it solved the problem. I bought a spare head shortly afterward, assuming that the L head may soon need replacement. Move forward to a month ago, and the problem began again. Banding started out of the blue one day, with no changes to setup, paper, custom profiles, etc. that have worked fine for hundreds of prints. All drivers, etc. are current versions.
Banding is horizonal (direction of print heads) and shows up on b&w prints; I can only see it in areas of little detail that are quite dark, about quarter-tone (i.e. dark areas of open sky). I've tried color gradation tests and can't definitely see banding there, although it's possible that there is a nearly undetectable amount on certain colors (it's so minor, if there, that I can't be sure), but very obvious on those particular areas of b&w prints, on drum scans of b&w negs and on grey gradation scales that I've created in PS.
I have spoken to Canon support 4 times for a total of about 6 hours. I've done multiple A-B cleanings; nozzle check is always perfect. I've done auto head adjustment, auto and manual band adjustment; no better. Tried printing through the PS print function (I normally use the Canon plugin), and have tried a variety of my usual papers (both gloss and matte) and quality settings. Max number of passes helps, but it's still visible, along with a pronounced yellow shift.
Canon replaced the R head in warranty a few weeks ago; no help. They had me replace the L head next (my cost, using the spare I bought last year) last week; again, no difference.
Have there been any reports of air in lines in these printers, or defective ink? Is there a way to force the printer to print only one of the 12 colors at a time, other than nozzle check?
At the moment, it seems to be an unfixable problem...am I missing something else that I could try?
Thanks for any suggestions!