I think you complained in an earlier post about the squaring plate being too low and suggested bending up the ends. You said it was too easy for the board to slide on top of it. Since no one else has a problem with the board sliding up onto the squaring plate, it seems like something must be wrong with your squaring plate. The tracking sensor (brass roller) is attached to the squaring plate and so tracking problems could just be another symptom. The top of my squaring plate is about 3/16" above the rubber belts. I suggest that you look at the rubber belt installation document:
http://www.carvewright.com/assets/se...drive_belt.pdf
Pages 8,9, and 10 show how the parts are shimmed with washers to deal with the thicker rubber belts. The shims raise the squaring plate and move the brass roller away from the belt. Also, you will see that the rubber damper gets a washer under it. Make sure that your parts have been properly shimmed.