I just installed a Newport electric wiper motor. I really didn't like the look of the switch knob. Here's my solution....sorry, I'm not clever enough to post photos.
1. grind off the tab on the bottom of the original vacuum switch.
2. remove the tab, spring, and threaded collar. You'll be left with the knob and a steel stub sticking out of it.
3. use this stub to hold the knob in a vise. Drill a 3/32" hole for a set screw on the back of the knob.
4. with the stub in the vise, gently tap off the knob. It's secured with a spline but easily comes off
5. tap the hole for 4-40 threads. Insert a 4-40 set screw.

I made a bushing to reduce the original knob hole size to match the electric switch but this will probably work without a bushing. Also I polished the the top securing nut to look like chrome. It looks pretty good.
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Last edited by 47 chev; 10/06/2023 10:33 PM. Reason: add photos