900 Maxtrac Manual Deviation Control done, BUT........

[Max-trac]

I am having trouble with the deviation varying too much accross 902-928.
I did the AA2LS manual deviation control mod.
I get a voltage swing of 9.6 to 0V. (and yes, I did cut the trace).

If I set the dev at 902, all is good until around 926 it drops rapidly and is not acceptable in the 927 range. (this is how it performed before the mod when using RSS to set the dev at the low end).

If I set the dev at 927, it is good but the low end is way overdeviated.
I also note that with my pot turned all the way down to zero, there is still deviation.

Has anyone taken this mod further????
Are there any frequency dependant componants to play with?