> 
> Well, Norton I is acting up again. The Ladung light comes on when you
> rev the engine higher.
> 
> I thten goes off at the lowest possible idle. Once it comes on, it
> remains on until you return to the lowest idle speed.
> 
> Weird.  Quite the oposite of what you'd expect.
> 
> And the belt IS tight.

Could be the brushes are bouncing at higher speeds, due to rough or out-of-round slip ring.

Check the voltage, and if it's below 14.0, remove the alternator and check the brushes.

Frank Mallory