My 250-300 was based on cold fluid. Even if the pressure was something absurd like 400psi, shouldn't the servo release with the pressure drop to 0?

So far the possibilities seem to be:

1) Too high pressure
-Argument against this that others have run higher pressure without servo issues. Why am I the only one to be experiencing this issue?

2) Mystery VB issues
-Funky OD/TCC stuff seem for this.
-Pressure return to 0 out of Reverse is against this, but who knows what it could have been when it failed initially.

I can rebuild this thing again by the weekend, but without knowing why it failed (I thought it was the servo design, then a case fault, now?) I'm very hesitant and on the fence in terms another rebuild and a manual ZF6 swap from a Ford.