I have posted here a couple of times about my 400 Farmall and my power steering problems. Mine had PS from the factory with all IH stuff. The post was tapped and plugged with a flat plug so that should take care of the oil flow issue. I have taken the 2 valves and the Behelan unit from a known running, working PS equiped tractor, but still nothing. (only when you work the inside valve) The hydraulics on my tractor otherwise work great. I have lost count of how much time I have into this headache, but I'm about ready to put a straight shaft in it and forget the PS all together. Any ideas?