Hey Nicky, the secret here is to use excess tinfoil from the hat, if there is such a thing

Actually that is not too far off. There is a lot of current going through that switch and if there is a somewhat loose connection there or or the switch is getting pitted inside it will generate heat and the more heat, the worse it gets until it fails. You will need a new switch and probably have to make a new connector for it. Use the yellow spade connectors that are supposed to be rated for 50 amps. I had to do this on an 85 i had that did the same thing