The cutting height control on my BX2200 doesn't match the actual blade height. Parked on my concrete (level) shop floor with the cutting height control set to 4", for example, the actual blade to floor distance is only 2.75". Using the mower manual, all of the linkages are set to specifications. Is this normal, or is there another adjustment I'm missing? I can't set the guide wheels to their recommended settings because they would run on the ground and hold the deck up. Is there a way to re-calibrate the cutting height control knob to match the blade height?