Gee Whiz, another printer problem

I finally got my Epson 1400 heads clean and printing a good full nozzle check, but ...

All the colors are now working perfectly, except the yellow.

Now the yellow ink is not printing straight yellow. It appears to be contaminated somehow, with black ink. Printed a full yellow purge pattern and it is muddy yellow/black (kind of a blackish green color).

I took the yellow cartridge out and looked at the probe that goes into the cartridge. It is clean. The whole tray under the cartridges is clean. I sucked out some ink from the yellow cartridge head probe (with a syringe) and the ink appears pure yellow.

I then, again, cleaned the bottom sides of the heads: in case some black ink was somehow there and affecting the yellow coming out. Ran the purge panel again and it is still the muddy yellow/black.

So, the ink going into the head appears OK, but coming out or what is put onto the paper is contaminated.

Is there such a thing that there may be bleed internally from the black head to the yellow head?

What is causing this and how to fix?

Thank you,
--
Gritty