Update on Farmall 400 power steering

I"ve been trying to get the power steering to work proper on our 400. So far I"ve put a new aux priority valve check ball spring(no change) Pressure is 0 on 2000 # gauge out of pressure port until ya pull a hyd lever, then goes to 1100 # got another priority valve, same results - 0 on 2000 # gauge until a lever is pulled then 1100#.
Read all archives on power steering.
Came to post about a plug used in power steering tractors to block oil passage to valves. Off come hydro valves. Yup there"s a plug in bottom most passage of the first valve but it"s loose and has no O ring. Mine is 1/2" long x 1/2" dia with a groove in on end and an odd 1/4" tip that"s misshaped on the other end. Can"t find this plug in online parts manual or the O ring. Is it suppose to be in the manifold or the valve? Mine has an odd tip on one end that looks battered. What holds this plug where its suppose to be? Mine can go in the manifold and pass all the way through the first valve. I assume this isn"t right. This thing is about to become a non power steering tractor cause it"s making my head hurt. Sorry for the long post just trying to keep it as close to original as I can afford. Thanks for the help. Tim from the Rocking TJC

Tim, haven't messed with the power steerings for a few years now so this is just what I think I remember.
Plug is short with a thin head or bigger diameter section on the end to trap plug in the recessed hole between valve and steering support or manifold. The longer straight section has a o ring grove. plug slides in valve, but pretty sure I have found them both ways. The bigger o ring needs to go back in recess also. Plug is part # 364880 R1 and o ring was # 355697 R1.
When I didn't have a plug and the priority valve was removed also, I have threaded hole in manifold with 1/4 inch pipe thread and put a flat plug that uses a allen wrench to turn it, in the hole. Tap just deep enough so plug is flush or little below flush. With priority valve removed I could wash and blow cuttings out from the other side of passage.
Don't know if your plug could leak enough to be 0 on gauge. Are you checking PS pressure in the line going to steering unit, preferably with a tee and ball valve hooked up between?

Mr Slater Thanks for the time to answer. I guess mines missing the larger flat head. What I did was glean the archives and found a solution of putting an O ring on it and cutting a length of round stock long enough to go through all three valves and trap the plug with the end cap. I put the plug in the manifold O ring end first. Seems to work cause lo and behold "I Have Power Steering Again". Thanks to all that have ever posted on this problem cause without the archives I"d be still scratching my head. Thanks again and hope I can someday help someone with a problem

Tim from the Rocking Tjc

Ps we got 2" of rain in last 10 days. its helped but need a few more of them rains. Hay is growing, cattle out on pasture