Mmm.. I just tried adding stuff to the end of a .zip and unzip still works on it. So I wrote a small program to look for 'PK' (multiple instances) and unroll the linked file into several "candidate" archives. Still no luck -- unzip complains on them all.

Cheers

Oops. BBS bug. I deleted my post as you were responding, it seems.

Well, I looked and there's no valid PK header, as much as that first one looks like it ought to be. The next couple of characters are supposed to be version numbers and they're not.