The adjustments are made on the outside on all of them that I've seen by lifting or lowering the outside edge, which in turn causes just the opposite effect on the inside front edge. I think you will find there are bolts with jamb nuts, that raise and lower the outside wall. There are also bolts in slotted holes that fine tune how far in or out the front and back ends are.
Make any adjustments a little at a time because changing one thing always effects something else.
All this assumes you have a garden variety rack and pinion style electric slide. If you have something fancier then things can be very different - and outside my experience. :)
