PIXMA MG7550 Broken offset vertical lines only on black ink

[Tom4103]

On my MG7550 printer all black vertical lines (e.g. when I try to print barcodes) appear as slightly offset lines, not continuous. Every 5mm or so the line is offset about 1mm to the left and then to the right. It only happens with black. Other colors are perfect. I have tried auto-align, deep clean without success. Any ideas out there? Many thanks.

Tom4103

[Tom4103]

Also, I just noticed, when printing barcodes, they are not evenly black, smeared and alternately really black and lighter.