The "SW" terminal would be the other end of the primary winding, where it connects to the points. When the switch is in the "OFF" position it ground the primary windings so no current is generated, no spark, and the saw stops.
If you have access to one of the point replacement modules, try installing in in place of the kill switch (one lead to ground, one lead to the SW terminal on your coil), sometimes the module will fire the coil when the internal electronics in the coil will not.
Mark
If you have access to one of the point replacement modules, try installing in in place of the kill switch (one lead to ground, one lead to the SW terminal on your coil), sometimes the module will fire the coil when the internal electronics in the coil will not.
Mark