i took the pressure reading off the lever for the bucket. 3 point hitch and mower deck are on the same lever, and move very slow when warm
I know you cannot post photos.
It certainly appears your $630 hydraulic pump is failing.
I am just concerned that something is not right elsewhere.
Your tractor's hydraulic system is an Open Center one so if a valve, say for the 3 pt hitch, is not closing off completely, the oil intended to pressurize the loader when you ask it to lift, is leaking off through a valve which is not closing and the pump is fine.
At some point you have to decide which is the best way to spend your $. Have a Kubota mechanic look at it or buy a new pump.
If something else is going on and you buy a new pump and still have the same issues, it will not be good.
Dave