When I bought the bike the kill switch was functioning but very...very sensitive. As well the end of the plastic thumb lever was broken off. Initially I rebuilt the broken piece using a plastic epoxy putty. The switch had become finicky and rather than experience one of those embarrassing and dangerous "surprise engine kills" while going down the road and inadvertently touching the kill switch with a winter glove while adjusting the mirror stalk -does it sound like this may have happened to me? - I took the switch apart and did some maintenance to it. I'll blog that separately. So, the plastic thumb part was weakened as I attempted to trouble shoot the switch. I cut a trough into the back side of the switch and fitted in a piece of 6d finishing nail.
Covered it up with epoxy and Viola...good for another 30 years.