Interesting fact: Did you know that german market MB5 & MT5 were not fitted with a horn?
Instead they had a bell fitted to the handlebars
(you can just see it under the right hand mirror (silver disc) on the MT5 above)
This is an actual bell taken from a German spec MB5
And just to prove this is not a wind up! note lack of horn button!
All the above pictures kindly provided by Tilo!