I worked on it for a while this evening. Still is not square but I think it is probably good enough for me anyway. It just bugs me. I took the positioner arm off from the fence. I checked it to see if it was square. This turned out to be a futile effort. At any time I could either make it square or take it out of square all with small enough movement you could not see it in the level. I also can make the fence square with the table surface by twisting it when the positioner is detached. I tried holding it in that position and tightening the positioner to the fence. This did not work. The screws pulled it out of square. I then tried putting a small shim on the bottom when ther control arm connects to the fence. This also did not appear to do anything to help. I also checked the rail height again and used my digital Bosch level so I could get a digital read out of the table surface and the rails. They are dead on according to that. I am not sure what else I can do to adjust it. But like I said I think it is close enough for me. The only time I might have a problem is if I am cutting something thick, or a board on end. Then it might start to be a problem. On boards under 1 inch thick I don't think it will matter.