You might look at the patents deposited in other countries too. They archives might be up online to different dates than our Italian one. The Italian patent office right now lets you search online only down to october 1989
In Spain it was Pat N. 204209 and Switzerland Pat N. 303990... the one drgary gave the link for is the patent for UK. I think I saw another couple around the internet but never really bothered saving them (sorry
) and right now I can find only those two.
As you can see listed even in the UK patent, the first patent date was 26 April 1952 which would be your reference for Italy.
And Gaggia, as company, passed so many hands in the last years that Im not sure how helpful they would be, at least through emails.
In any case all I ever seen about those patents doesnt have much more than what you see in the UK patent, like 3 sheets listed and nothing more. (I'm not even sure if there is a difference between documentation for the appication of a patent and the published documentation after the patent is granted, in all the patents I saw I havent always found a detailed description of every single part even if it was marked out in tech drawings)