I have an old used Craftsman table saw. It works fine most of the time, but will start to seize up when cutting boards when the blade is raised more than an inch and a quarter. My assumption was that as the blade rose the path of the center of the blades rotation would stay a fairly constant distance from the motor. However, as the blade rises, the tension on drive belt keep increasing and is adding load to the motor. I'm concerned I'm missing a part that keeps the correct tension or would correct the path of the blade relative to the motor or is this functioning as designed.
Is this one of the old Sears models where the motor hangs off the back on a hinge? The weight of the motor supplies the tension. It is possible that the hinge is frozen allowing the belt to over tension. Ideally the motor should be free to move as the blade is raised and lowered. The pivot bolt should be tight enough to prevent lateral movement (left to right). It should be loose enough that you can raise the motor by hand. The belt tension is determined by the weight of the motor. I have seen people even hang scrap metal (window weights were popular) on to the motor to increase tension as the belt ages and begins to slip under load.