550 - External Control Valve- HELP IDENTIFY

Well I broke down and brought my hudraulic cover in to the local AGCO mechanic. Just got it back today, but I am still concerned. He did not have a whole lot of experience working on the 550 hydraulics and only had the I&T manual to go by. I am still waiting for my real shop manual CD. Here is what he did find. On the front of the hydraulic cover is a pipe plug, it is just to the right of the filter. Behind this plug is another plug with an allen head to remove it. This allen head plug had a very small pin hole drilled in it. The mechanic said because of this hole the system was not able to build full pressure for the three point. He braised it closed and told me to try it out. My second concern is the external control valve has a "cartridge type" rlief valve in it which says 2250 psi stamped right into it. The mechanic said this relief valve was never actually even utilized since the allen head plug had the hole in it. I know that the relief valve is only supposed to be 1700psi and do not want to break anything by running the high valve.
Also, he said that in order for the three point to work the fluid has to cycle through the external control valve. I asked if there was a check valve and he said "no."
This is a photo of the external control valve on my 550. Notice the red paint under the green. This valve does not match any of my photos in my manual. Is it Original equipment? Or even Oliver equipment?
Thank You for any advice.

I Have the same part on my 550.
the hoses are connected on it.

did you have your answer?

What did you use the hydraulic for when it was working right?

Did the tractor have a loader on it, and if it did, what did you do with the holes when you disconnected the hoses?

That block looks to me like it is a block for a power beyond hookup, not a external valve.

Since we both have the same units, which were both taken from 55 or 550 models its not coincidnece, but it may not be original, but it sure looks like it to me. The castings are very similar in design. But I am no expert.

Through Paul and this site, Mike M also was quite interested in this unit and he had it for a while to study it. He sent me a nicely detailed letter on it about its use and installation. I have it in the shop, I will dig it out. email me at stu&brenda at telus.net with an address or a fax number and it will be done.

If you had a parts book it would be a lot easier to describe what to do.

First, as you have the cover off, turn it upside down. About halfway up (longway), and off set from the center is where the retainer for the spring and bypass valve is at. You will want to check to make sure it is clean and working free.

Next, after you put the cover back on your tractor, run a hose from one hole in the power beyond block, to the other hole. If everything is then working correct, hook up your loader, as before, and try it.

As for welding the hole that the mechanic did, I don't know about that.