Lee Seats article in ShopNotes, H-10 "Turn Signals; Don't Throw Away that Old Sparton Switch", prompted me to repair the unit I had. The original wire covering was bad but the switch tested good. So new wire, cleaning the switch contacts and some paint and I've got a like new turn signal switch. The following is pictures, a video and diagram of my repair.
Short video to demonstrate how the return wheel, which rides on the steering column, functions.
Sammy doing a wiring crunch test.
The switch was not taken apart. Electronic cleaner that I used.