Digital BW, The Print

Recently, I've been having problems with my ABW prints having a slight
(but unacceptable) greenish-blue cast. I'm using a r2400 with the
standard K3 inks. I've run a head cleaning cycle, and the test pattern
looks OK. The problem is quite subtle, but very apparent if you
compare prints I've done recently with some from a few months ago.

Any suggestions as to what might be going on?

Thank you in advance,
Sarah

PS: Sorry if this message turns up on the list twice -- I think my
first attempt to send it failed, though it's possible that the first
message may just be delayed.