So, one of a couple of things has happened...
(1) The server or the file running the old forum has croaked, based on the error message that's seen when the old forum is accessed:
(2) The license expired early and isn't valid at this time.
Once Ira sees this, he will be able to provide a better answer.
Right now, it simply seems to be 'it's gone' - until when or if it's resurrected.
As far as the Internet Archive...start here, but I'm telling ya, there's not a lot there, I'm afraid.
https://archive.org/web/