like most things lambretta, it costs money.
Get a Stickys manual for sure. You won't regret it.
I'm not so sure how active the LCUSA forum is, most people are on facebook now. I'd join a few FB groups and see which ones are active.
For most simple things you could use some of LCUSA's sub-forums. if memory serves, you could buy and sell, etc. but some tech help required additional membership.
I was able to scrub older forums, scoot BBS
https://www.scooterbbs.com/ to find info on an li190 that I had bought, reading through the previous owner's posts, that kind of thing. That's what people did in early 2000s. Before that i think they used carrier pigeons.
I'm into Lam conversions, which is a level deeper so I scrubbed the series six forums at one point for people that were shoehorning typhoon forks into lambretta frames in Surrey and Essex or wherever.