If it is off by a large amount, I'd call Service regardless of the actual problem. It seems that this tool should be very close from the factory. Mine, for example, required no adjustment period. I did check it using the various methods in the manual and in YouTube videos, but it was such a minute difference that attempting to make any adjustment would just likely make it worse. When I use it, the result is perfect according to my eye, which, in the end, is the only thing that is important. If the whole project goes together and it looks as if everything is square, I can't ask for anything else. I made some drawer boxes as my first project and, without clamping, the corners were a perfect 90 degrees. So, no matter what the differences are on the Domino, they are not significant.