John Deere 650 Loader Hydraulics

I am installing a Westendorf loader on my John Deere 650 and cannot get the loader to operate. My tractor had no additional hydraulics - no power steering, no Selective Control Valve. I purchased the loader new, direct from Westendorf, with all of the parts, including the control valve. I installed the loader per their instructions along with the help of John Deere's technical manual. Everything installed with only one issue...
The problem I have is the loader will not lift. The loader will only lift when the 3 point hitch is lifting. The loader will drop, due to weight/gravity, when directed to drop by the control valve. It will hold once lifted.
I have installed the power beyond plug behind the outlet port on the tractor, per Westendorf's instructions and per JD's technical manual for the tractor. The tractor acts like the plug is NOT installed. The plug I used came from Westendorf, just a simple plug. Is the plug from John Deere something special?
I took the tractor to the local Deere dealer who tested the hydraulics and found pressure, relief valves, and flow to be within specification. They did not indicate the plug was wrong or the wrong type.
I have narrowed the problem to one of two things:
1 - The tractor is somehow bypassing the auxiliary circuit? The 3 point hitch works as normal all of the time. My understanding is the purpose of the power beyond plug in the tractor was to force the fluid through the auxiliary circuit, then back to the 3 point hitch after the auxiliary circuit.
Here is what has me perplexed about the tractor --- If I leave the power beyond plug behind the outlet port of the tractor, disconnect the lines to the loader circuit, and replace the two plugs blocking the out & in ports of the auxiliary circuit on the tractor, the 3 point hitch [u:1b3cb26e01]still works[/u:1b3cb26e01]. Based on the technical manual & my understanding of the system, the 3 point hitch should not be working if the power beyond plug is in and the two ports are blocked. It seems my tractor is not properly routing the fluid through the auxiliary circuit, even though the plug is in. Anyone know why not? How is the fluid getting around the auxiliary circuit back to the rockshaft?
2 - The control valve Westendorf sent me may be the wrong type of valve? They have sent me two valves because we thought maybe the first valve was bad (The John Deere dealer's suggestion). My understanding is when the Control Valve is activated, fluid should route through the loader to the out port & dumb to the reservoir. I only get dump to reservoir when the loader is dropping (due to gravity). I do not get fluid dump to reservoir when I ask the loader to lift. This indicates the system is not putting pressure on the loader circuit when asked. The JD Tech manual states the system needs an open center valve. Could I have the wrong type of valve? Is it possible the valve I have is open to the power beyond port & the out port when activated? If it is, wouldn't the fluid take the path of least resistance and just dump through the rockshaft instead of going through the loader?

I have been working on this installation for 4 weeks, which should have been a 6 hour job. Any ideas or thoughts are much appreciated.

I have a 750 and have hooked up the factory control valve but it has been years ago.
The special plug is just a metric allen screw. There are 2 hex plugs on the front of I think a relief valve housing. I forget which one it goes into but that allen screw goes into one of them it is threaded back inside. You need an open center valve with a power beyond port. A pressure hose goes from under the seat I forget which port up to the inlet of the control valve. A hose goes from the power beyond port back to the other one under the seat. A hose goes from the return port on the valve to the side of the transmission case where there is another hex plug you remove. Somewhere I should have the factory inst. to install the control valve. I can dig around and find them if you need to know which port is which if your instructions do not tell you this.

Thanks Mike.
I have all the connections in place and complete. Westendorf, local JD dealer, and the tech manual all confirm the connections are correct.
Top plug under tractor seat is the IN, which gets connected to the Power Beyond port on the CSV.
Bottom plug under tractor seat is the OUT, which gets connected to the IN port on the CSV. Inside the bottom plug on the tractor is the threaded hole for the hex allen plug. The hex allen plug is in place & tight.
The transmission case gets the OUT port from the CSV.

All that checks out with our tractor. The valve must be wrong or set up wrong.

Yes - it seems to me the valve is not correct.
If the valve is correct, then somehow my tractor is diverting flow around the auxiliary circuit.
I am going to perform some testing on the valve to see if I can confidently track down the problem.
Thanks for the help.

All,
I have solved my problem.
I removed the hard line between the 3 point hitch and the rockshaft housing. In the hollow bolt that holds the hard line in place I found a stripped small hex head plug. After removeing
the rockshaft housing, I found inside the outlet of the rockshaft houseing a small threaded home for that plug. This is not the power beyond plug, but another smaller plug that comes in
90 degree to the power beyond plug. I replaced the stripped plug with a new one, and everything works correctly. This additional channel is NOT shown in the John Deere repair manual
for 650 & 750 tractors. My guess is the plug was not inserted correctly when the tractor was built, causing the treads to strip originally.
It all works correctly now. Thanks for everyone's help.