As far as i know, it works like a big Ponte Vecchio Lusso. I'd disassemble it and give every part a good cleaning. Doug and Barb from
www.orphanespresso.com can help you with parts. Every part that can break can be replaced.
Paul Wilmott-Dalton is also very knowledgeable on old levers.
Take your time.
There are a multitude of restoration threads on this website. I'd give them a good read.
After you get it up and running, get some good fresh beans and a good grinder, you'll wonder how you ever could be happy with the Saeco.
Restored old levers are much more valuable, but two groups will never be as valuable as 1 groups because they are simply too large for most people.
Here are some pics how your machine could turn out when you've cleaned and polished it.
Lever Lust - 1956 Faema Urania