Through the opening of the service mechanism dust and sand comes enters in spite of a dust seal, so the whole thing looks like pictured here. For this reason it is advisable to dismantle the carburetor regularly and to clean the diaphragm so that the function of it is provided.
In order that to do the 3 screws are loosened at the diaphragm chamber and the lid is removed, hold the lid, because otherwise the spring, mounted behind it jumps away. Afterwards the diaphragm can be cleaned. Also the service the mechanism now the lid is removed.
Because this carburetor is even more in the position to pick up dust and sand, the Austrians ate fitting a bigger and more downwards pointed protective covering that also does work perfectly on a Yamaha.