switch?

Hello, new to the site for me and I'm finding a lot of useful info. I recently bought a doodlebug that has the clone 6.5 on it. It doesn't have the adapter plate so the motor sits to the right side of the bike when sitting. It runs ok but I'm thinking about going a lil smaller just to putt...

How do these in line brake switch work? Is there something missing?

Does anyone know where to get a fuel switch that mounts on the carb on a DB30? My sons broke off so I called Baja Motorsports and they said it is part of the complete carb and they did not sell that part indvidually. If anyone knows where I could get one my son and I would greatly appreciate it.