Ink marks on PIXMA Pro-1 prints

[Chiotas]

Hello guys,
I'm an happy owner of a PIXMA Pro-1 printer, but I have an issue that I'd like to discuss with you in order to find a solution.
If I print on a small format paper like A4 (210×297mm / 8.27×11.7 in) or A6 (105×148mm   / 4.13×5.83 in) I get some black ink marks on the paper.
On the A4 size, I get those marks near the border, on the A6 size exactly on the four paper edges. No any Issue on A3+ paper size.
I'm almost sure that they are roller marks, and for this reason I tried for several times the automated "feed roller cleaning" and "bottom plate cleaning" but with no results on the print results.

Any suggestion?

I think the reason is that the Hahnemühle paper that I use in small sizes often comes bended (in fact A3+ size Hahnemühle that is absolutely flat has no issues).
Am I the only one experiencing this issue?
Is there any other way to clean more accurately the rollers in order to use paper not perfectly flat?

Thank you!

 

[howardm]

without actually seeing some samples/examples, I'd venture that the paper is in fact slightly curling upwards and/or you need to set the printers 'gap' somewhat wider.

[Chiotas]

Thank you so much for the reply howard!
As soon as I'll come back home (business trip) I'll post you some sample images.
Just a noob question in the meanwhile: what do you mean exactly on setting wider the printers gap?
Thank you

[howardm]

on inkjet printers, the head 'flies' over the paper with  a very small 'gap'.  Most printer drivers allow you to change that (often separately from the paper thickness setting).  So, if you have paper that is slightly curling upwards, it can catch on the head as it flies by.  Increasing the gap often helps.
As does reverse curling the edges of the paper just before printing.

[Chiotas]

Thank you so much for the hint! I'll check if this function is available on the Pixma Pro 1