last night it was a flat and tonight its the hydrostatic drive on my Quick 36". Any ideas on what could be wrong. I engage the throttle and the wheels won't go. I can see the axle spinning but no power in the wheels. I pick up the back end and pull the throttle and the wheels spin but once it touches the ground they won't go forward or backward. The brake also does not engage when I let up on the throttle, like it normally does. Any help would be great. Thanks. Ben Baumgart B2 Lawn Co.