Steve,

That is a 3-pin Twist-Loc connector. The center pin is ground. Of course you need an in-line female. It may be the same connector the 28 ROTR uses. I may have one. When I am up to walking around to the cellar in this 20 degree weather, I will look in my Twist-Loc box.

I also plan to try to take a keytop off and back on to my 15 to see how it is done.

When I tried to look up the connector, all I found were 20 and 30 amp generator connectors. Still the small ones might be available at a big electrical or electronic supply house.

Tom   N3CRK