Hello, recently my L185DT seems to lose hydraulic strength after it's used for 15 minutes or so. The FEL wont lift or tilt with any load in the bucket and the three point will barely lift with the box on it. The oil strainer is clean, I checked/cleaned the relief valve/seat to no avail. The tractor has no leaks but was a little low on oil. I topped it off, but it had no effect. It seems to work fine when first started but quickly gets worse as the tractor warms up. Any help is appreciated!