Thanks for this hint. In fact I might consider a repair. The speedometer I have is set on KPH and not Miles which is something pretty rare. The 69 bird was apparently exclusively imported to Switzerland in Europe. The one I own was imported from the US in 1989 and maybe one of the old owners found one on the Swiss original spare parts market.There is obviously no possibility to find this feature on the US aftermarket parts.

But I will first take it off an have myself a close loot at it to see if I can see spot anything obvious that could cause the trouble.