D-19 power steering, again

I am still trying to figure out what is going on with the D-19 power steering. Took the sheetmetal and raditator off last night and did some checking. The return tube is going down into the oil quite a ways, didnt measure it but about 3". I made up adapters and vacuam and pressure checked the entire suction tube assembly, no leaks. Also made up and adapter to spin the pump with my drill and (supprize) it still foams the oil. The power assist is nothing short of wierd as you would expect with the systems operating on oil froth. You turn the wheel and meet stiff resistance, and about a second later the power assist comes in and turns easily. If you put it against the stop it pulls the motor down a bit and you hear the by-pass squealing. There is no growling or howling like you would expect from frothy oil just normal pump humm. The only thing I can find is there is a small amount of slop in the pump bushing, just did a wiggle test no indicator. There is no leakage at the shaft seal. In my past experance pump seals leak oil out when bad, not suck air? No service parts available for the pump anyway as far as I can tell. New pump equals $1100 which makes for darned expensive guesswork. Can a bad pump shaft seal suck air? For those tha have not followed this ordeal A year ago I resealed the valve and cylinder and that had no affect on the problem. There is so much air that occasionaly when you shut the tractor off it will puke a bunch of oil out the breather.

What are you using for PS fluid?

Your suckn air. I rebuilt my ps pump from the seal and bearings I had purchased at bumper to bumper which turned into o'reilys now.