I have a GJ that is in great shape, runs excellent and looks good. However my 3 pt system can not pick up weight. If there is around 250# on it, it will slowly lower down. The fluid is the right, hydraulic fluid, and the level is good. We are trying to figure out why. One thought is the high pressure relief valve may be bad. Or the piston rings on the hydraulic piston that lifts it may be bad. Any thoughts??