My 3rd Gen. Faemina has a small leak of steam from the lid cap. It happens when the machine reach full pressure.
When looking at the part scheme I can't see any component that can prevent such leak.

I have a new cap, and all the parts are present. Am I missing something?

P.s. I apply plumber tape under the lid (where the bolt enter the lid), but still I get a small leaking.

You're not missing anything, there's just the nut up against the metal cap. The pressure release valve should be releasing most of the pressure, the Faemina hums like a freight train when it's up to pressure. Maybe make sure that the nut is positioned in such a way that it's up against the lid when you tighten it down. I suppose you could put in a washer between the nut and the lid to help, but it's not in the design.

Thanks Chris for clarifying this. Now it makes sense.

FWIW, Francesco started including a seal for this in his kits a few years back. It's not in the original design but clearly others have encountered this issue. It's the smaller clear seal that is depicted inside the large boiler cap seal:

http://www.francescoceccarelli.eu/Faida ... C_0692.JPG

I bought the exact kit from Francesco, but I probably skipped this seal.
I put similar one, I had on my work bench from other machine, under the lid and tighten the nut. it's solved the problem.

Thanks.