It is on the side of the switch. once you remove the switch there is a little hole with a plastic holder in it. Slot screwdriver and you should be good It is similar to the ones for the ECT/Defog buttons.
I love the term "Classic car" I remember those switches. It seems to me that they were on ALL north american cars until somewhere in the mid 80s If we didnt have to replace them every 2 years from salty boots I would probably still use one. There is no fun anymore like back then. Hit the switch...
