There are are a few observations I have after reading the post... If it is binding and releasing the problem is not in the tune. I would focus on the center support bolt being loose or broken from being overtightened.

There are a few other possibilities, but in the end it needs to come out and be disassembled for inspection and repair. The key is it is not holding Direct and is binding on the 1-2 intermittantly.

g

 

^^^^ bingo.....

I'd say possibly the sprag as well given the info from post #1.... I asked a reputable builder I know just as a what-if.... And that's what we kind of came up with...


But hey.... WTF do I know

 

That was my thought all along, not the tune.
I posted up to try to figure out what might be causing it internally, as I am not a tranny guru.

Tranny is being sent back to FLT, lets see what they find.