Vertical Change in Shadow Density at 16"

[Digross]

I've never seen this before and cannot find any comments about it.
My Epson 7600 shows a change in shadow density, looking like a vertical line, at 16" from the right. The bar is actually a change in print density in shadows. The change is only visible in shadows.
- Epson Enhanced paper
- Atkinson profiles

The problem goes away with the "Super" setting on (but that introduces other problems).

Please help me!

 

[The Hat]

I have experienced that type of flaw (Mark) on certain photos myself before and the way I got round it was to save the photo file in a different format, or change the App I was using to output the file from, I never did find out the true cause for it..