I just spent a few hours of my morning re-installing one of the two Atlas under the table switch machines on my layout. It went smoother then the first installation, but it still was a major pain. The switch machine has just enough throw to move the points from one side to the other. If you have it at a slight angle to the track centerline or off center, it doesn't quite move the points all the way over to the stock rail. It was working for a while, but recently my engines have been picking the points on a consistent basis. After 3 installations of these finicky machines here are my suggestion for installation: 1. Draw the track centerline on the bottom of the table. This way you can check if the switch machine is parallel with the track once you have an approximate position. My first installation was a bit crooked and this reduces the range of the throw. 2. Use tape. I put a piece of packing tape over the motor portion of the switch machine with the ends hanging off. Once I had found what I though was a good position for the switch machine I could press the tape onto the bottom of my layout. This held it in place while I crawled under to check the alignment and screw it in. 3. Look in the hole. I found it easiest if I could look down the hole and see the position of the switch arm relative to the sides. You may have to put a light sheet of paper or light the area beneath the layout if there isn't enough contrast to see where the arm is positioned. In my case I found that the arm was hitting the side of the hole near the end of the throw and that is why it wasn't moving the points far enough. 4. Work from the thrown positions, not centered as the instructions suggest. IIt is easier to push the switch to one of the thrown position when it is under the table then to center the arm. Throw it one way and see how much space is between the wire rod and the centerline. Throw it the other way and make sure the rod ends up the same distance away from the centerline on the opposite side.