I couldn't find a UK alternative to the £20+ dealer switch but (after some searching) here in the uk Radio Spares (RS) have an alternative - same size, easy fit (when you don't drop the tiny screws) and about £5 inc. postage stock no. 517511 Description - leaded button V4 switch ip67 MPA DC3C-C3AA Just fitted it and works fine for me - (you could check the amperage) only 2 of the 3 wires required (check) and solder. It is possible that the small actuator pin is worn but it can be seen (working or not) at the side of the brake with a torch- its's about .2" diameter and 1.95" long - easy enough to find a piece of plastic and sand to size.
Yep - makers used to be called Cherry and they make good micro switches. Omron do the same thing, it is an industry standard. FYI Cherry used to put together Harley handlebars
