Hi
1951 Light 15 small boot attached is a picture of my indicator switch, if you can wait I will be attempting to re wire next month and I can post if you are interested.
On mine the dip headlight is switched of when you go to full beam, it took me a while to figure it out.
There is a basic schematic on the site in the technical library,mine has been heavily modified and rewired in the past is making it more interesting.
Well I was going to attach but the new site has lost me, I think your switch looks like a chrome cylinder were mine looks like a conventional indicator stalk.
Will try and figure out this new site when I have more time.
Dave