Man when you find out let me know. I've got the exact same problem, except with a Cub Cadet rider. I've done the same things you have. My solution was to let the air out of one of the tires on one side and then adjust the deck all the way down on the same side as the flatter tire. Then I put 3 new blades on. Looks ok if you mow on level 2 but it's still not level!