Is it a 1 touch adjust (adjusts the hieght with one lever) If so, it sounds like something is bent causing it not to adjust evenly. If its a seperate hieght adjuster for each wheel, check to make sure they're all on the same hieght. If that doesn't fix it, put it on level ground (pavement preferably) and measure the 2 sides of the deck, they should be the same hieght off tthe ground, if not, it's a problem with the wheels or adjusters, if the hieght is the same, it's a problem with the blade setup.