Retrofitting of Hydraulic System

If you know who the manufacturer is, I would contact them for recommendations...If you don't, I would spend some time trying to figure out who the manufacturer is....It's hard to make specific recommendations on a generic piece of equipment...other than to say take it apart and refurbish or replace everything....In some cases this may not be practical....

New gaskets, o-rings, seals, compression shims.....and a good quality "oil" resistant sealant applied only where permissible together with correct assembly practices should tidy that up.

New hoses too while you are at it.

Following the previous advice on cleaning prior to disassembly will make the job a lot easier and aid in successful leak amelioration.

You speak of inefficiencies, as well as leakage. As stated above, the leakages should be fairly easy to isolate. But if the leakage is from corrosion in the manifold, it may require replacement id severe. If that turns out to be the case, I would find a hydraulic repair facility that is well established, and local. Take some advice from the people that will be able to service it after instalation. There are packaged hydraulic systems that include pump with reliefe valve and reservoir that would connect to your existing motor, or engine. You would then need to add the specific valve system you are using to it. This is where the local hydraulic repair facility would be helpfull in determining the size requirements for you. Good luck.

Manifold part number or detail drawing may not necessary to make spare manifold. Any hydraulic system supplier can make manifold if schamatic diagram and valve model numbers are available. It seems to be simple one with one directional valve and pressure relief valve (position of relief valve is not clear from the description, it can be in P line or port line). Standard subplates and connecting piping can also replace this old manifold.

It will be helpful if you can give valve model number and functional details of application.