Canon IP6000D shows heavy green tint on grayscale

[wainrights]

Canon IP6000D shows heavy green tint on grayscale pictures. This shows
on any image, regardless of the source. No problem on black text.

I performed recommended maintenance, like deep cleaning, nozzle check, and alignment -- no problems there.

Black ink and cyan are "Low" but high enough left to normally print perferctly.