I scored this weird/interesting machine at a local sales website (Romania). After struggling with carrying it up to the apartment the fun began. The machine is in incredibly good state apart from a lot of dust from the time it has been inactive there is no limescale deposit no rust no missing parts, the lever was running quite decently and all in all it is waaay better than expected.

And now the fun part
- how could I tell if the spring needs replacement?
-how can I find/ match a new group for finding the parts that need to be replaced?
-where could I find more information on this machine?

I will post more photos along the way and if anyone can help please let me know.

Congratulations, nice find.
Take a lot of pictures, during disassembly.
The issues of repair will come as they go.
Only certainty, all joints will have to change.
good luck.