My load leveler is not activating? Just hooked up the car hauler with a M715 on it, about 7500 lbs. Safety chains were resting on the ground! Pulled forward a few feet and the rear end had raised about 4 inches about 6-8 inches lowere than usual? Cut on and off a couple of times to see if it would kick in, with and without the tow button in, no dice. Any one had this problem before???