QTR-Quadtone RIP

Hello,

I used to profile my old 1290S and the 4 gray shades with very plesant
results. I moved to a R1800 to reduce clog issues and increase (if
possible) the smmooth transitions of my print.

My trouble is: Making a profile (following the regular procedure) I
obtain some small bumps (few %) on the response curve (I try 21 and 51
- measurement with a ColorVision spectro). They are still present
after linearization (even lower) but I can see them on my print.
Also, I found that the ditther selection change the position and the
imporatance of the "steps" I see on my prints (???)
I seems to me that it's easier to profile with less gray shade...
Maybe I shoudn't use all the shade K7 and go back to K5 or K4 (???)
Do someone have some advices?

Thanks
Christophe