I don't know where to start, even to determine what parts I need to fix the hydro. All I know is it does not work! I can see oil running out the breather pipe and I don't even know where the hydro pump is located. I am guessing it is either at the front of the engine since that is where the hoses go. The hydro system may also be a part of the belt pulley setup near/under the steering wheel column near where the breather is leaking. That is where the reservoir for the oil is located. You can check the oil level there by opening a plug. It seems to me that the hydro oil reservior and the oil reservoir for the rear end of the tractor are located inside the main "tube" frame of the tractor. Could they be allowing the oil from the hydro to spill into the rearend gear box because of a bad seal? I understand the rockshaft is what lifts what I would call the lift arms of the 3 point hitch, that is under the seat and has what I am guessing is the hydro lift cylinder inside a casing at that location? I did have a repair manual but it is so poorly reproduced that is is hard to read let alone understand the illustrations. I gave the manual to a guy that fixed the carberator and put in an electronic ignition. He unfortunately died without returning it, I did get the tractor back however! The tractor now starts good and runs pretty good except the governor is not working properly and the engine surges when pulling heavy. Thanks for the patience as I learn from you all about the mechanics of this tractor.