The headlight Hi/Lo beam switch has always been stiff in operation but lately it seems to be getting stiffer. Having read about the perils of ballistic springs I approached the job with care. First thing i encountered was what I believe was a non standard bolt holding the switch together, a hex bolt with slot which I replaced it with a Allen bolt. 

I carefully disassembled the switch in a ice cream bucket with a rag over it to contain any errant parts. In the process of working out why the switch was so stiff the switch contact block had to be removed multiple times. On the final test the switch block went too far allowing a spring to make a bid for freedom. 

A search of the floor failed to find it, so I had to find a source of a new spring. I had previously repaired a switch on another non Bavarian bike with a spring out of a cigarette lighter. I don't smoke but I have always carried a lighter as part of my tool/survival kit. On disassembling the BIC brand lighter and with a bit of trimming the spring was a good match. 

You should get 3-4springs out of a BIC spring. A bit of grease and relieving the detent hole has fixed the switch action. The errant spring has since made an appearance. Two more BIC's have been added to stock.
Regards Martin.

Good to know Martin.  I have a Hi-Lo switch to repair for a friend and will use this tip.