Canon S9000 - purple band at end?

Hi all,

I've got a 1.5 year-old Canon S9000 that started showing a single light 1/8" wide purple band, all the way across, about 1/4" from the end of the page. I'm printing with a 1/4" margin, so the band is actually about 1/2" from the end of the paper. It shows best on dark or shaded areas.

I've checked the heads and they appear reasonably good (a few isolated segments missing in black, and one in cyan) and aligned the print heads (F needed a minor tweak). I can't see the yellow test-grid well enough to tell if it's OK. I don't know whether this yellow visibility is just due to my vision, or whether this is just difficult for everyone to see. I've used plain paper and semi-gloss.

Has anyone seen this end-of-page purple band? Any solutions/suggestions?

Steve.