On my '07 the rear leg has a height adjustment, so you can adjust the slide up and down to level it. Both the front and rear legs are rack and pinion driven, with the pinions being chain driven. To adjust, I would assume that you would have to remove the chain from one of the legs and then adjust the other one one tooth at a time until they are equal. Biggest problem is taking out the portion of unbelly to reach the chain. Alfateers in California bought the remaining parts from the factory before it closed, so they might have more info than I can give you.
03 Silverado cclb 3500 drw, D/A, Reese 22k hitch
07 Alfa SeeYa Gold 30RL,2 slides,power everything