jurden, Hooked_on_HP
This is just a thought. I seem to remember that some solenoid valves had a manual release on them. Do you remember what the top of the solenoid looks like. Is there a cap, and is there a twist knob of some kind. If it is , screw the spool all the way open, on the grapple circuit. Try working this spool back and forth to the limit. There may be something preventing it from opening all the way, and reducing flow. Did you say that you had taken the spools out and inspected and cleaned them? That relief valve should not be going off for the work port for the FEL, because any flow to the grapple should keep the pressure low enough to keep it from opening.
Have you put a gage in any of the circuits? That will let you see the operating pressure, and the relief pressure. Because all fluid going to the front goes through the FEL valve, I would install the gage in the input to the FEL valve, and leave it there for all future trouble shooting.