You should be able to use the V1 for test purposes, if you plug it in and everything works then you know something is bad in your V3. The switches should be available at any Electronics shop, but electronic shops are getting pretty hard to find, especially since the demise of Radio Shack. If it were me, I would simply twist the wires together in a constant on position and then plug in the battery and see what happens. If everything works fine then you know it's the switch, if you still have the same problem then you know it's not the switch.