When using the Pappasana Nuvita 1965/1966, the liquid spills out

When using the Pappasana Nuvita 1965/1966, the liquid spills out

The lid of the Jar in the Pappasana Nuvita 1965/1966 does not have an hermetic seal, therefore, when the blades are operated, the food must not exceed the line that indicates the maximum level shown on the glass. Beware not to insert more food than indicated by the manual