When I installed the new sonnax boost valve it gave a procedure for wet testing the pump for leaks. I did and it had cross leaks in the pump assembly, while adding pressure to the torque signal orifice it would leak out between the castings pretty good, the reverse boost orifice wasn't as bad but leaked also.
I had to find a piece of flat glass and used some 320 grit sand paper on it to flat sand the pump. It was a little difficult to work around the stator shaft. Sanded both pieces.
My ATSG manual says nothing about checking for cross leaks, how much can be tolerated? My home grown resurfacing made a pretty good difference but it still leaks very little.
The manual does not even mention it so that gives me the idea it's not critical. In the real world is it normal for it to leak a little or should it be air tight?