Yellow/Black cross-bleed Artisan 1430

[Chackers]

For some months I have had a problem with cross-bleeding between yellow and black, more often with the yellow jets squirting black, but sometimes the other way about. Temporarily fixed by head cleans followed by printing blocks of colour until clear. I have been away for a month, and today, on my return, everyting was pretty clogged, so in the end I very gently syringed 1 part Windex glass cleaner to 6 parts isopropanol into the inlets to the print head. To my horror, I found that on squirting into the yellow, ink flowed out of the black. Does this mean a broken internal wall and a defunct head?