I had a similar problem on mine, the low beam on the left light didn't work, so I replaced it. Then it did it again a few weeks later, so I bought another bulb, from the local gas station, so it was expensive. Then after throwing away the old bulb, the light failed again, and I discovered the plug was a bit dodgy, so fixed it. So... I'm pretty sure both new bulbs were unnecessary. Pays not to jump to obvious answers, huh?
open the switch and spray with contact cleaner,then spray with acf50 or similar, worked on mine, it's like a new switch now.
It was not exactly that, but it help me found the trouble.
In the button, there is a small spring that keep a little copper piece which make the contact, to the different cable. This small spring was not enough strong to keep the contact. I just add a small rock (it was the only thing I add around me!)
So this was the way I resolve my problem.
:-) I can now go and rode at night!
End of thread · 7 posts recoveredWayback Machine snapshot 26 Oct 2014