Mr. Stern registerred 5 machines for patent in 1953.
The inventions relevant to the model 402E were granted.
These improvements made the production of these machines faster, as well as use and maintenance easier for the customer: refilling the water tank, dropping the coffee filter or changing the seals... the machine opens wide.
Here the original patent:
(please note the little picture was sticked by the secretary and wouldn't have appeared on an original document).