Tom & Guy,
Yeah, my first action was to take off the controls with the 3 spools and have a reputable hydraulic repair shop rebuild them. Supposedly, they all looked ok, they did find a piece of rubber from one of the cylinders packing, but other than that it looked fine. Regarding the pressure regulating block (one of the big problems is that every manual I read has a different name for these things), if I'm correct, this is the same as the pilot relief valve? It is adjustable and regulates the pressure for the entire bank of hydraulic spools.
I had to make a tool to adjust it, basically a 3/8" pipe, cut on the end leaving two tits that engaged the adjustment. It had to fit over a threaded screw and inside a threaded bore to engage the adjustment. I adjusted it in and out without any change to the problem. I think that only leaves the relief (check?) poppets for each spool. Supposedly after 40 years of wear, they can wear to the point of sticking and allowing the flow to avoid the rams. I suppose I should take the whole damn thing off again, but that took half a day last time. I'm hoping I can just take them out and see what I can see. I replaced the filter and all the fluid a couple years ago, probably should have done it when I bought it in '84, but oh well.
Regarding parts, since International went under, it has gotten harder, and there may be esoteric transmission bearings or something that are impossible, but Case and various other manufacturer's still carry most of the parts. The challenge is finding the part # and paying the bill. I just bought a steel tube and seal for the hydraulic pump - 1" diameter, 2" long, $40 plus shipping. What are you going to do.
On the other hand, I just rebuilt the engine several years ago and it runs like a top now. It is the only tool I have that will pick up the 1000# of my listeriod and ST5 gen head, carry them up the hill and place them in the frame I have bolted to a concrete foundation. Soon I hope.
Ray