Digital BW, The Print

First of all, the system I am using:
Epson 10600, reconfigured to use Cone K6 inks. I am printing through 
StudioPrint (RIP). I have new banding issues. The banding is in areas 
of smooth tonality- sky is a special problem. The image that is 
causing me the most pain is from a digital file- Leica M9- that I can 
print (same size, same file) through an Epson 7880 using ImagePrint 
and get no banding, perfectly smooth tones.
the problem is in the 10600 but what can I do about it?
I have tried inverting the image but the banding appears the 
same...nozzle checks are good.
Any help would be appreciated!
Paul


-- 
Paul Kohl
Visiting Professor
Art, Design and Media
Nanyang Technological University
Singapore