Hi folks.
As I also frequent 2 German forums here is an interesting story.

When trouble shooting the engine for no power in the upper region, the carburator, which was cleaned one week before was taken off and opened up again.
FOUND 2 LITTLE FLYS IN THE BOWL.
Apparantly the 2 breather hoses were just beside the square frame tube and not inside so they where in the airstream and the flys entered the hoses