I have been thinking that my bladespeed is low. The quality of the cut is off bad anI can hear the blades slow. If I go really slow it mows better but that's super slow. I have all new belts and blades. I can't help but think it has something to do with the engine. I have the hight set at 3.5 and after I mowed today I went back over the tart and it looked like it cit another .5 inches off. Any ideas about what will cause the blades to slow.