It's normal to be able to turn the steering wheel after the wheels have stopped turning with the danfoss type orbiter. before you touch the orbiter, replace the filter next to the steering tank and change the oil, it doesn't take much, around 7Ltr, and it should be ATF oil, then check the pump pressure, on one of the output pipes from the orbiter, the relief valve is in the orbiter and you can damage the pump unless you have the correct equipment if you simply put a guage on the outlet side of the pump.
I dont know the correct pressure for your tractor, but other makes are 175 bar at the pump and a relief valve shock setting of 160 bar, with a working pressure on the output side of 100 bar or 1450 psi
