Digital BW, The Print

Since I only get this list in digest form, if you can help me, please
respond to me @: markmaio@...

I am running the Piezography inks (warm neutral and selenium) on an Epson
7600. It usually sits for weeks without use, so I ran some large grayscale
test prints through it yesterday to get rid of any bad ink in the lines.
After (6) 13 X 19 prints (3 run with each ink set selected via StudioPrint),
I got a very nice color/gradation pattern on the third print of each ink
set. I did a nozzle check, had 1 or 2 missing lines, did a standard cleaning
and with a good pattern started printing after doing a head alignment.

I did a standard print I use as a comparison print to make sure everything
is printing the same, it looked great and I began making new prints. A few
hours later (and maybe 20 sheets of 13 X 19), I noticed a slight "blue" cast
to the blacks. I did a nozzle check and the "Y" (far right of the seven
nozzle test patterns), was so faint, I could just make it out. I did a
number of standard cleanings, maintenance cleanings from the menu, turned it
off and let it sit overnight, checked the posting on various sites and did
some KK2 cleanings and while the nozzle pattern appears to be a bit darker (
or am I imagining it is), it does not have the density it needs to print
correctly. 

Any help you can give me will be very much appreciated as I planned on
printing for an exhibition all day.

Thanks,

Mark Maio