When you pulled the clutch pack to look at the clutches and steels, did you go one step farther and pull the piston out and check it's seals? You were already there and just had to pull a couple more things off to get the piston out.
Also, you can pressurize the case holes with air pressure to hear the clutch packs compress before you put it back in the car.
Get a service manual. It is all in there.