Brush cutter hydraulic question (relief valve)?

I have a brush buster with Eaton hydraulic motor and it has a pressure relief valve (block) before the motor. Hit a stump and the mower will now only engage at about half throttle or less, when you go past half throttle it shuts off. I am guessing the relief valve was damaged? These are nearly $1000 to replace on this model. Can they generally be repaired or must be replaced? Any help would be much appreciated? Thanks

Are you sure the hydraulics on the machine are still in good order? Need to know that before you condemn the brush cutter. There may be a relief valve on the auxiliary feed on machine messed up.Your description is sort of vague-you say it shuts off-the auxiliary pressure from the machine kicks off or the mower quits spinning and when you throttle down it starts spinning again?The hydraulic motor may be bypassing internally or be damaged. Is the relief valve remote mount in a block or bolted right to the motor? Could you bypass it and see if the motor works then or is still weak? Before you buy a relief valve for the cutter and possibly throw 1000 bucks away you need to dig in a little more.

I could by pass the relieve valve, but it also acts as a brake to slow the motor down after shut off and I am afraid if I bypass it when I stop the auxiliary it will cause the motor to come to a sudden stop rather than gradual and may damage it.

Is the $1,000 from the dealer of the brushcutter, or the hydraulic manufacturer? Have you tried to cross any numbers on the relief valve?