B2 piston-cannot move from bore

[mwalker01]

83 Mercedes 300TD 123.193
Transmission 722.3??

1) Recently replaced the B2 piston in my transmission. It came out in pieces when I pulled it out. The car had all the classic symptons.

2) At the time I did not have a manual, and assumed that the thrust pin that was removed was internal to the old B2 piston.

3) Installed the new B2 piston without the thrust pin. Obviously, it did not correct the problem. I then bought the transmission manual and realized how the thrust pin is supposed to be installed.

Problem now is I can't remove the B2 piston. I want to avoid pulling the lower cover, I am afraid of being able to get it back together.

There is no clearance to get the thrust pin in without removing, I tried pushing the brake band in, could not access the small end of the B2 piston.

The piston will move within a certain range, there appears to be some vacuum holding it in from complete removal.

Is there a way to get the B2 piston out, like draining the valve body, or applying air pressure to release the vacuum?

Thanks.