hortimech

You might think everything is working correctly, but let me assure you that isn't. I didn't spend 25 years of my working life, building, servicing and repairing Kubota tractors without learning something, you really need a 3 port spool valve. I have seen split top cases caused by using the wrong spool.

It looks like your spool valve only has two hydraulic pipes going to it, if so, then it is the wrong spool. you need a spool valve with 3 ports, in, out and power beyond. the in comes from the take off block you have fitted at the front, out dumps back to the axle and power beyond is the return to the take off block. If you don't use the correct spool, you get back flows etc and strange things start happening. You should also check that the PRV in the spool is set lower than the main tractor PRV.