Digital BW, The Print

Good afternoon folks,
 I'm in a tizzy over this problem with my Epson 1280 printer, which
did not start till the last refilling of the cartridge a couple of
days ago. After filling I failed to get a complete nozzle test
pattern, so I kept trying up to 3 times and then printed a small print
and let the printer rest overnight after cutting it off and parking
the head on the waste pad.There is ink in the chamber but it fails to
print at all. I have used 1:10 mixture of amnonia and water on the
parking pad and also to rinse off the cartridge bottom itself. I even
reinstalled QTR with no resulting changes. I even inserted a color
cartridge to see if it was the cart itself but it failed the test
also--no light cyan output. That's how I narrowed the problem down to
nozzle problems. I took the UT2 cart and put it into the color Epson
1280 and ran a test print through it using the same QTR printing
engine as in the BW printer. That print was ok as was the color
version of it using the MIS color ink cartridge. Up until the
refilling of the UT2 cart, I had had no trouble with nozzle
clogging/air bubbles to any serious degree. I was printing something
every day. Now I am experimenting with color so I have not used the BW
printer every day. Could a clog become so entrenched that nothing will
remove it? I hope someong can give a direction for me to follow to
resolve this issue.

Your friend in Photography,

Johnny