S_,
I just looked to be sure on my 69 factory wiring diagram and there is nothing between the switch and battery. You can use a ballast resistor to drop voltage, but the 12 volts through your switch should go to your solenoid to operate it and that will cut the heavy current through to the starter. Make sure that you don't have a short somewhere that is pulling to much current through the switch. The solenoid is just a heavy duty relay. Make sure it hasn't shorted the primary winding straight to ground. And as you stated, a bad switch is a possibility also. Even a piece inside the switch could have came loose and be shorting. Ballast resistors are normally used with the old points and coil distributor set ups.
Ron
