w00t! The smoothing groups were already defined, it turned out - I didn’t need to do a thing to them. The problem was solved the moment I took your advice and used weld on all the vertices. It was down to my SMD importer losing the smoothing for some reason…
He’s still got one or two other little bugs but I think I can handle them from here on in. Thanks a million for all your help!
Nice nose though, eh?
EDIT: Just a note for anyone who had the same problem - the real issue was my exporter plug-in, as OpethRockr55 suggested. I was using it because I had 3DS Max 9 and Cannonfodder’s plugins weren’t compatible with 9. I tried this project again on my friend’s PC, (he has 3DS Max 7) using Cannonfodder’s importer/exporter and it worked like a charm. Looks like I need to downgrade!