Digital BW, The Print

>... 60% 65% & 70% all appear to print nearly identically.

>This is with the Paul Roark r220 icc, ...

And the paper is the one specified, I assume.

The flat spot is where the cross-over is between the light and dark inks.
If the light inks were too dark or dark inks too light this is what would
happen.

Have you tried printing with no ICC?

> ... "how do i modify the icc profile ...


This is the file on making an ICC with a flatbed scanner:
http://home1.gte.net/res09aij/Making_B-W_ICCs.htm  

If you have a spectro it's easier.

You can also just make a Photoshop image adjustment curve and use that with
no ICC. 

Paul
www.PaulRoark.com