QTR-Quadtone RIP

I suspect that the some of the Cone K6 inks that I just put in in fresh unused cartridges may not be good anymore. I am getting a pronounced flat spot in my lighter midtones of a 21step grayscale file. The ink I used came from the last 20ml left in the 2 year old bottles of K6 ink shades 1-5. While I realize that the inks don't go bad per se, I suspect I did not agitate them enough when I used them last, 18 months ago. 
In order to test these old inks, I would like to print a square grey block using only one of the 6 different shades at a time and compare the result with fresh inks in fresh carts.
Is there a way to use QTR to tell my epson 1400 printer to use ONLY the ink shade #1 in the first print, then use only shade#2 in the 2nd print etc.?
ron
Mac os10.6
epson 1400
Cone K6 Special Edition