Digital BW, The Print

Hi... as I've said before in this group, I'm new to the world of digital b&w printing.  
Just a reminder to those who don't recognize my name  :-)

I've been happily printing with UT7 on a 2200 for a couple of weeks now.  Tonight, I 
made a print that was unexpectedly high in contrast and was quite yellow too.  Sort of 
a split-toned effect with its blacks being blue.  I tried another image, one that I'd 
printed last week, and got the same result, so did a nozzle check.

The light cyan cart appeared to be completely absent, so I did a series of head 
cleanings and nozzle checks.... which brings me to my question.

I expected the checks to get progressively better with each cleaning cycle, but they 
didn't.  Rather, the clogged head would get better, I'd get a near perfect check, run 
one more cleaning cycle, and suddenly another color would be partially missing.  In 
this erratic way, after 6 or 7 cycles, I finally got a good nozzle check.  Is this sort of 
clogging behavior normal?  What might it indicate?  And is this a good time to ask for 
a link to procedures that may minimize clogging.  For example, I've been leaving my 
printer on.  However, I've just returned and received a replacement for an R800 
because of an unclearable clog and during this process Epson tech support advised 
me to always turn the printer off, even if out of use for as little as 20 minutes.  So I 
began applying that principle to the 2200 as well.  Perhaps turning it off precipitated 
this clog?

any comments, advice, links, etc., appreciated
Ed