Canon IPF8300 printhead alignment failure

[mooc0w]

I recently acquired a Canon IPF8300 at auction, and I'm able to reliably get quite good prints from it with the exception of slight alignment problems between colours in prints.  It has a perfect nozzle check, and also a perfect service mode nozzle check, for all colours.  The left head is new, with only 2000 mdot printed on it.

The problem comes when I try to perform any of the head alignment options, the yellow channel prints badly, and then just drops out, with the alignment obviously failing.

Standard alignment adjust:
IMG_20171027_203336.jpg

Advanced alignment adjust:
IMG_20171027_203322.jpg

Behind both pictures are sheets of yellow printed out between each alignment attempt -- they are absolutely perfect, with no dropouts, banding or any other issue.  I'm tearing my hair out here because it doesn't seem to make any sense.  Does anyone have any ideas what might be wrong?

[deanwork]

I've never experienced anything like that. But if it were me I would delete all the software and reload the latest version to rule out any software glitches before considering a service call . And I would try a gloss rc paper to align if you aren't using that already. Even though you see no nozzle problems do one head cleaning anyway. That's all I can think of.

I recently acquired a Canon IPF8300 at auction, and I'm able to reliably get quite good prints from it with the exception of slight alignment problems between colours in prints.  It has a perfect nozzle check, and also a perfect service mode nozzle check, for all colours.  The left head is new, with only 2000 mdot printed on it.

The problem comes when I try to perform any of the head alignment options, the yellow channel prints badly, and then just drops out, with the alignment obviously failing.

Standard alignment adjust:
IMG_20171027_203336.jpg

Advanced alignment adjust:
IMG_20171027_203322.jpg

Behind both pictures are sheets of yellow printed out between each alignment attempt -- they are absolutely perfect, with no dropouts, banding or any other issue.  I'm tearing my hair out here because it doesn't seem to make any sense.  Does anyone have any ideas what might be wrong?