Non Synchro O/D--help

Been having trouble with an early O/d since it was rebuilt. Electrics all work good. Took the plug off the actuating valve (on top) and it was clean. Took the plug off the non-return valve (below the pump) and cleaned it. Reassembled the bottom end and ran the trans to about 2000rpm. Got some oil to flow out of the actuating valve but it just kinda oozed. Put the whole thing back together for a drive. The first few times the o/d worked but as the oil warmed up, the o/d would go in and out. In fact, under a load it won't hold at all.
How do I check if the pump is putting out enough pressure (I wonder if the pressure is too low to keep the o/d in)
Second--anyone near Atlanta know where to get this one sorted out professionally?

in the seloniod there is a ball bearing and an O ring. That ball bearing is a PIA but it is the heart of the OD operation that lets the oil move around the OD and that O ring, it is always over looked, if it is old or dry it can leak dropping pressure and kicking it out of OD......get an O ring and try it, just go to where they have a gazillion O rings and find a an exact fit..... 40 cents with of parts to try before the big bucks kick in. happy trails.

Are you north or south of Atlanta? Know of 3 mechanics who should be able to help. Call me at 7 449-9090..........