Digital BW, The Print

I have been using MIS UT2 inks in an Epson 1280 since last fall with 
wonderful results—within three weeks of receiving the printer, I was making 
better prints than I ever made in the darkroom. As one of a legion of "silent" 
onlookers, I have benefited greatly from this forum and read it daily. Now I 
have a problem with my printer (no, not clogging!) that has me stumped.

    I don't print sepia, so use LM in the yellow position (the spongeless  cart 
filling sequence from left to right is C, LC, M, LM, LM[in Y position]). Several 
days ago I refilled the cart, using inks from an earlier order except for the light 
magenta (LM), which I took from a recently purchased bottle. When I resumed 
printing, the prints were dull and muddy, with compressed gradation in the 
dark tones (and the 21-tone test chart printed with little differentiation from 65 
to 85%). I printed the 6-color purge pattern and found that the LM/Y position 
was very dark, close in tone and hue to the M patch. Thinking that I might have 
mistakenly put M in the LM/Y position (unlikely, since the LM and LM/Y 
compartments were filled sequentially from the same open bottle, and I only 
open one bottle at a time), I rinsed out that compartment thoroughly and 
reloaded it with the new LM. The results were the same. 

    The answer would appear to be simple:  MIS sent me a mislabeled bottle of 
LM ink, possibly containing M ink.  However, several other observations do 
not support this possibility:  (1) although I refilled both the LM and the LM/Y 
compartments from the same bottle, the LM patch in the purge-pattern print 
looks just as it should (about the same tone as the LC), and (2) to see if the 
suspect ink was indeed M rather than LM, I diluted out aliquots of the M and 
new LM inks and the found that the LM does appear lighter than the M (that 
doesn't confirm that the LM is formulated correctly, but it is not identical to M, 
although it appears so in the purge-pattern print).

    So, it appears that the LM ink in the Y compartment of the cart is for some 
reason printing much darker than it should. If this is not a banal problem 
involving the wrong ink, what are some other possibilities?

    For whatever it is worth, I uninstalled and reinstalled the Epson driver with 
no effect on the problem. Nozzle tests look fine (after the usual round of 
cleaning cycles). I'm not sure what to try next.

   Any suggestions will be appreciated.

Jim Congleton