Is the clutch line too close to the exhaust pipe? Too much heat can boil the fluid.
If you pump it up but don't drive it, and come back several hours later, is it good or bad? (If bad, it's leaking...)
Oh, one more possibility. I'm not familiar with the construction in there, but hydraulics pushes the TO bearing out and the flex plate pushes it back. There has to be enough "friction" to keep the TO bearing from drifting farther from the flex plate fingers or you'll get the behavior you descrtibe as you pump the TO bearing back up to the flex plate.
The Constitution needs to be re-read, not re-written!
If you can't handle Dr. Seuss, how will you handle real life?
Current oil burners: MB GLK250 BlueTEC, John Deere X758
New ride: MB GLS450 - most stately
Gone but not forgotten: '87 F350 7.3, '93 C2500 6.5, '95 K2500 6.5, '06 K2500HD 6.6, '90 MB 350SDL, Kubota 7510