The cut off switch is one with a On/Off twist. It is connected to the positive battery lead and the switch is under the seat on the valance. The battery is just over two years old and had a two year 100% replacement warranty. Fortunately the shop was kind enough to accept the late date and gave me a new battery.
The cut-off switch has been in use for over 10 years with no issues.
I have the impression that the lever was stuck on the brass button and that caused the failure. The spring under the button intact and the spring pulling the lever back is not weak.
I have since cleaned the pivot points on the linkage and put light grease on them. All seems okay now.

1949 Chevy 1/2-Ton
"Sedgewick"
In the Gallery
1989 Caprice