Got an H30D in the shop with17000 hrs, its a 351J06076230 ser#. The problem is when moving in either forward or reverse the machine seems to lurch as if the brakes are dragging or there is a problem with the pump. it is has the 2 pedal system one for forward and one for reverse. We've tried pressure tests and come up with nothing. it seems to get worse as the oil gets up to temperature. their doesnt seem to be noise from pump cavitation and the oil doesn't look aerated. any suggestions wuold be great