Hmm... thanks for that info BDI.
I was, however, hoping that somebody in SoCal was gonna be able to tell me "Oh yeah... just go to this store called (BLAH-DEE-BLAH) they have everything like that.
Anyone?...... Anyone?
Well, its an flanged head M6 X 1mm threaded bolt, all you have to do is find the right length or buy a long one and cut it down with a hacksaw.
The head is indeed 8mm across the flats and its about 25 mm long, if you get one longer its a doddle to cut down though.
I assume you have industrial fastener shops over there?
Do you still have the other bolt on the other side of the headstock? If so you can take it into the industrial fastener shop and say "get me a few of these" and you will have some spares for next time it happens.