ok ive had this cub for 3 or 4 years now, the usual procedure is turn fuel on, use the tractor, shut down and turn fuel off,tractor is a dailey user as im pulling a small feed trailer with it [ old pickup bed, with 250 gallon tank in it] and mowing when i need to, yesterday same thing, but, when i went to turn the fuel off the lever wont turn, i mean its solid in place, i dont want to force it, even though i did gently experiment with a small pair of pliers,the lever will not move its solid, the nut is tight on the sediment bowl,but i can loosen the nut and the lever still wont turn, and nothing else has changed lucky so far, as it hasnt put any gas in the crankcase, yet, so whats going on here before it mess it up what do i need to do to it???