it would be helpful to know where the strikes occur (mid page, edges, trailing edge, dark areas, etc etc).
The paper is 2.7mm so setting to 3 is the absolute minimum and I'd probably shoot for 4. Also, 'Widest' may be a win
too. have you tried smaller sheets and seen the same problem? Have you put the sheets on a flat surface and checked if the paper has curls or buckling?