On mine its not exactly the switch that was bad. It was the wiring on the starter that was bad. Previous ownder didn't tighten the wire connections. So I lost the fusible link; Then I had a bad negative batt. cable causing other issues like slow starting, slow windshield wipers, some lights would work then not work etc.....
Now that I repaired the fusible link at the starter, and tightened the battery ground, I have head lights, tail lights, inst. lights etc.... all again. I just left the new light switch in because I figure its cheap insurance for the future. My truck has had lots of starter issues since before I got it. I think either the electical issues finally killed it off.... Or my wiring was bad and that's why it won't start now. I will be looking at it later. Good luck !