This is something I've seen before with this paper, and I always thought it was just "in" the paper as it is a very regular rippling of the prints, parallel to the direction of travel. But today I noticed that it's not in the paper (mostly appears in areas of high ink density, and not at all in unprinted areas) and that it perfectly aligns with the spacer "glides" on the vacuum strip of the 9800. I've tried turning the vacuum down to -4 (which seems to turn the vacuum off)..and lowering the ink saturation slightly....and it only improves things very slightly (at the risk of a scratch in the same direction as the ripples I've tried increasing the paper thickness setting and that removed the scratch. I've not seen this on other similar papers, but curious if anyone has seen it and solved it with Platine Fibre Rag (as I do love this paper very much).
Thanks
Barry