The copper lugs in the switch are probably not making contact with the copper lug on the starter. Try operating the switch with a large screwdriver or a tire iron and see if any sparks come from under the switch. If I needed to buy a new one, I would get one from Steiner's Tractor. Better quality repro than the typical offshore auto stuff. They answer the phone and are cheerful and want to help. They also have Delco style points that are all metal. Reasonable, too.
