Digital BW, The Print

Hi, all. I'm a long-time epson group groupie, mostly just lurking 
and learning from you all for the last year or so. (Too busy 
moving and printing....) Thanks for all the great posts.

I have a problem with a sudden color shift. Any help would be 
appreciated.

 I've been using Generations inks on a 7000 to print "toned" 
black and white photographic images on Bright Cube paper for 
some time. Not an easy path, but mostly rewarding. However I've 
had two episodes of severe Epsonitis that has wreaked havoc 
with my work. I'm in the middle of one of them now.

What happens is that at the start I'm able to print a reasonably 
close greyscale using custom Photoshop curves on my RGB 
files. (So far I haven't been able to make or even edit a 
satisfactory profile, and neither have Profilecity or a couple of 
other people who have tried. But that's another story) What I get 
for neutral is not perfect, but it's close enough so that after 
"toning" with even more curves and other layers, my output looks 
pretty good. 

When the problem starts, though, my grays shift radically, all of a 
sudden becoming cyanish-green. (And of course, all my work 
grinds to a halt.) Nozzle checks look fine. All other colors are fine 
and black dithered to gray is fine--the problem is restricted to 
grays and near-neutrals printed with color inks.

The first time this happened, I made a bunch of careful new 
software adjustments to compensate, only to have the printer 
slowly return to "normal" (after quite a bit of printing). It was a 
mystery.

This time, a file that  printed fine one night printed cyan/green the 
next morning with no changes in settings. Nozzle checks are 
fine. I haven't changed any inks.

I have an Epson tech running me and the 7000 through all the 
usual hoops. We've eliminated any possible software and 
interface problems by printing through his laptop and using 
Acrobat instead of Photoshop. Results are exactly the same as 
with my setup. 

Of course Epson wants to flush out all the Generations inks and 
try Epson inks. I'll go along with that, but I see no reason why this 
kind of radical change in gray tones, with all nozzles firing, 
should be an ink issue.

Does anybody have any ideas? My best guess is that the board 
on the print head, or the printer's main board, is flakey. 

The only other thing I  can imagine is that the inks separated or 
changed in some way. I was out of town for a couple of months, 
and the machine was only turned on and off periodically during 
that time. Still, the nozzle checks have been good right from the 
start, and the first printouts I did when I returned (two weeks ago) 
were not cyanish/green. 

What would cause a sudden change like this? Any similar 
experiences out there?

Thanks for any input.

--David Stock