The next thing you need to do is a compression check. I had a D850 that was doing the same thing and found the compression was very low. I took the head off and the pistons looked fine in the cylinder but when I removed them and 2nd land was broken on all three. I assume that last owner used...
2 Spool 8 GPM Prince MB21GB5C1 DA Valve w/Float | Directional Control Valves | Hydraulic Valves | Hydraulics | www.surpluscenter.com
Here is another one that may better suite your needs.
This one is close to what was on it originally. It also has option for Power Beyond if needed.
2 Spool 25 GPM Prince RD526GCGA5A4B1 Valve w/Float | Directional Control Valves | Hydraulic Valves | Hydraulics | www.surpluscenter.com
Yes, it was at my cabin in Colorado and I am taking it back out in a few weeks. It t will be used to move snow and work around the cabin as before, but it will be stored inside now.😉
it took 3 months. I am semi retired so I devoted quite a bit of time to it. The key to a nice restoration is complete disassembly, attention to detail, shop manuals and of course money.