I do the 11 point calibration 0-100%. Of course, the set only has the offset/gain for the white balance. I wish it had adjustments for each level, I'd love it. So it is always a juggling act between the cuts and gains.
I found an old cal from 2009....it was much, much better! But the set has tons of hours on it, i don't think it has the legs anymore. As I mentioned, if there was a way in the service menu to adjust some of the settings, maybe it would be possible. I just think its just age and wear.
I may tinker with it, but the answer may be that it just ain't possible given the age of the set.
I will look at the 30/80 windows again to see what I can do....