Use my 656D hydro to operate a nine foot discbine. While mowing on a hill recently the tongue swing cylinder on the discbine would not operate until the tractor reached level ground. Power steering too was hesitant. When making a particulary short turn on the steep side of the hill the tractor acted as though I had pushed the foot and inch pedal in and then suddenly lunged forward. Tractor seems to be starving for hydraulic oil but the indicator stick shows full. Hydro filter was also changed recently. Is there a pick up tube on the intake side of the hydaulic pump that is broke? Open for thoughts and suggestions.