Edge 800 electronic spares

Hi@All!

I'm searching a source of getting this micro-switch on/off of my edge 800, which is placed on the side of the platinum. The Button broke first, and the switch fall out afterwards. Any suggestions, or original part-number?

As far as I know now, it's a neuralgic point of these builts! 

Thank you for answering !

Best wishes from Rendsburg Germany, Peter