Brake lever pin keeps falling out

[CyclesnIPAs]

I run Avid Juicy Carbons and the pin that holds the brake lever into the master cylinder keeps coming loose, sliding down and almost falling out. I probably wouldve lost it if my shifter wasnt there to stop it. How can i fix this?

[cobba]

Sounds like you have a similar problem to: http://forums.mtbr.com/brake-time/please-help-id-avid-juicy-brake-part-834855