Hydraulics:
Type: open center
Valves: 0 or 1
Pump flow: 7.8 gpm [29.5 lpm]
Steering flow: 3.5 gpm [13.2 lpm]
If FEL works, you have flow through all the valves to tank.
You are talking about the 3pt will not lift a bush hog.
Is the bush hog to heavy?
If you installed a hyd gage in a tee in the IN port of the FEL valve, you could monitor and trouble shoot the hyd system.
If the gage were installed and you raised the lever, you would see the pressure required to raise the bush hog.
If your 3pt valve is good, then the seals on the 3pt cyl is bad and bypassing the fluid.
Do you have hyd input going into the 3pt?
Some people using a BH, will bypass the 3 pt system.