Digital BW, The Print

Is anyone else having problems with UT2 (eboni black) inks.

I have an Epson 1290 and have had the UT2 (eboni black) CIS for 
around 8 months. In the last two weeks the printer has started to 
print my black and white prints with a reddish/magenta hue when 
before they printed neutral. Since having the printer I have topped 
up the 4oz bottles with eboni black ink and yellow and that's it. I 
have tried the swab test on the MIS site and the colours look 
correct.
I seemed to have tried everything to correct this problem but 
nothing seems to help. I am using Adobe CS2, and have tried the quad 
tone rip but again with similar results.

I have phoned MIS and they could not help with this problem and 
referred me to Paul. I have since heard that there was a bad batch 
of Light Cyan with too much magenta in it. I cannot recall whether i 
have topped up my cyan but will have to check with MIS. If I have 
been sent a bad batch of MIS inks, what are MIS going to do about it 
as it has completely screwed up my printing work-flow and I cannot 
reproduce those prints that I currently have exhibited in the 
gallery that represents me. 

Paul suggested i agitate the inks and I have done so, and will try 
and print a large batch of proofs later to see if this has any 
effect.

Does anyone else have any suggestions  to correct this problem, as 
it looks as though i will have to dump my 1290 and MIS inks if this 
problem continues. Would probably consider buying another 1290 and 
possibly MIS inks again as the carbon ink prints i have 
produced are excellent, but am not happy to hear about bad batch's 
of inks etc..