Help with vero fat boost

[Droogie]

Hi all. Just finished a vero fat boost from my7of9's update of renegadrian's layout. To my delight it fired up first time. A real treat for a noob such as myself. 
My issue is with the gain and volume controls. The volume is at unity when maxed; the gain acts like another volume that also is at unity when maxed. When both are maxed I do get a fattening effect. (Does this pedal make me sound fat?) Any ideas as to where I should start looking?
Thanks!!