Canon MP780 prints yellow-green

[dynawriter]

Everything except black text has a yellow-green tint when I print color with my MP780. Grayscale printing is fine.
I soaked the printhead in Windex, cleaned the purge pads (but didn't clean the purge lines with fishing line), aligned, head refreshed, and cleaned. Nothing helped.
This started about the time I inserted an Inkstop big black cartridge. Any problems with Inkstop? The problem continued after I went back to Canon cartridges.
Should I try a new printhead? The 4-year-old printer is about $150 + shipping on ebay; printhead is approx. $50.
Thanks, in advance, for help.

 

[dynawriter]

I talk to myself out loud; now I'm doing it in a forum.
Just found the answer: There were 2 photo carts, magenta and cyan. Replaced those with regular carts (1 Canon, 1 Inkstop) and all is fine.