Take them up on that offer. As of my last post I was thinking that both rears were overhanging and that both fronts were good. That would have been weird. Again, its hard to tell from pictures, but it looks like the rear is skewed slightly left, so an adjustment might do it.

My old one had carriage bolts through a rubber stopper and the stopper fit into the stake holes. When the carriage bolt tightened, it expanded the stopper which held the cap in place. There was another adjuster, sort of a collar on the bolt, which was eccentric. When you cranked that, it moved the bolt sideways, giving you 1/4 in. adjustment to each corner. Probably better tech today, but it almost has to be adjustable.