[Nima]

Okay, I pulled the transmission again and took it apart and looked for any broken seal or other things. I took the input drum and put it back together with new sprag although the old one still looked okay to me. Since the all other parts were new including the pistons, I test fit them for being snug when put together, I put everything together. When I pressure test the input drum using air compressor setting at 40 PSI, I get a leak which comes from the hole the center of input shaft inside the drum (there are 4 holes, 3 seems to have a ball in them and one without it) when I test 3-4 clutch (the hole closer to drum, at the same time I am blocking the release hole on the side). The forward clutch and over run clutches seals very well.
I thought I may have damaged the pistons when I installed them. I took the drum apart and installed new set on pistons. The same result
Is the drum bad? I don't see any visual defects.
I appreciate any help.