I know how hard it can be trying to track down these kinds of problems, especially when there are so many moving variables, so bear with me while i annoy you with more questions... How old are the inks and did you give the bottles a good shake before installing them? Or, are the some of the inks newer/older mix? Is this a new supply of paper? usually these things might not matter as much (aside from pigment settling in the bottle, but all your test charts look good so I am leaning more toward a problem with the profile)
Do you have any Hahnemuhle photo rag or Canson Edition Etching on hand? I have profiles for those papers that don't exhibit the same kind of banding that are evident in the supplied MIS-EB6 profiles. I can send you one to install and see if it is the paper/profile or issue with the printer.
Before we get there though, I have a few other thoughts. can you go to your QTR profiles folder (it should be application>QuadToneRip>Profiles>1430-MIS). Then open the .qdif or .txt file that is giving you problems (in text edit) and then copy and paste all of the text into your response... it should look like this:
PRINTER=Quad1400-MIS
CURVE_NAME=RB-Eb6-HnPhRg
GRAPH_CURVE=YES
N_OF_INKS=6
DEFAULT_INK_LIMIT=0
LIMIT_K=32
LIMIT_C=45
LIMIT_M=45
.
.
.
Then, you navigate to the following folders where the actual profiles that the printer uses: "yourHD">Library>Printers>QTR>quadtone>Quad1400-MIS (or Quad1430-MIS)
Open the profile that is giving you this problem. It should have exactly the same name with a .quad extension instead of .qdif/.txt (this will open in QTR CurveView and show a graph of your ink curves) and then make a screen shot of it to post to the flikr page (cmd+shift+4 will give you the crosshairs for defining the screen capture area).
From your scan, it looks really grainy, and not at all like it was printed from a 6 dilution ink set (i know that is what is loaded, and what is being printed with the calibration page, but if the profile isn't calling for those other inks then they wont fire)
Please post the exact file name of the profile you are using as well.
This should allow us to see if there is something obviously wrong with the profile before moving on the next step (like going Office Space on the damn thing)
Richard Boutwell