Thats a stuck 1-2 shift valve in the valve body.
Did ya take it out and rinse it while moving the shift valves with small screwdriver or seal pick?
Even if the valvebody was rinsed out, the valves must be moved to make sure the original debris that caused the problems in the first place are cleared from the bore sealing surface of the valves.
Most every valve in that valve body has a spring behind it (behind being relative)
But you can move them one way or the other with a small flathead screwdriver.
Move them all back and forth in thier bores and I'd bet you found one that is sticking.
That one will probably be the 1-2 shift valve.
