Mike,
It took me a while to realise that there's a tiny little grub screw (allen bolt) in the pivot point of the lever that you tighten up, and not the big nut that I tried first. The instructions are a bizarre translation from Italian (as bad as BabelFish) and not very clear.
This pic should help you find it, although if you're tightening that already, then I don't know
http://www.chathamclose.com/pics/mc1.jpg Jason
[Edited on 18-6-2004 by Mr_S]