Situation: Right hydro/wheel motor is seemingly very weak and has gotten to the point where if on any kind of incline whether going up or across the hill (with the right hydro on the lower part) the hydro cannot generate enough power to really move it. If I release the relief valve and move the lever back and forth as though I was through to drive the right wheel only, in forward and reverse, a for 15-20 sec or so it restores alot of the power, but it quickly goes out. This randomly started doing this, and used to I could "pump it up" and it would be fine fore that yard or so, but now it just looses power before I can even make one pass across a yard thats not even 200 ft. Sounds: Make a clicking sound and stressed sound almost like the break is on, kind of a whining but not really. You know how hydros sound you can hear them from across the street. Take that sound, multiply it x 2 or 3 and then imagine it sounding sick at the same time. haha I know that desciption sucks but its the best I got. Possible causes: I let my father use it one day to cut his yard and I walked outside and found him about done and cutting with the parking brake on! It appears as though the parking brake puts more pressure on the right hydro than the left, so I thought this could have been something that although, not immediately causing damage, GREATLY shortened the life of the hydro pump/wheel motor. Mower: 2007 Lesco Commerical Plus 54'' Hydro Mower (the one with the floating deck) Has 150 hours on it. Question: -What could it be? -Can air be introduced into the system even if nothing had ever been adjusted or messed with? -If not air, am I looking at a pump or wheel motor? Any help would be greatly appreciated. This is my main money maker and I need to get it fixed ASAP!