I dont mean to offend or imply anything negative, but you did torque them to 72 inch pounds, not foot pounds right and then back off and torque the jam nut? If you dont hold the inner adjuster with a wrench while tightening the jam nut, the jam nut will drag the adjuster along with it causing too tight of an adjustment.
The forward band is so easy to adjust..... I personally would try backing it off another 1/2 turn.
I too agree, most shops wont do anything that you cant and likely wont want to mess with a trans modified by someone other than them.
If the simple band tweak doesnt work try changing the valve body. I have a couple of known good stock ones that I would send you to try if you want to experiment.