[Sammus]

Have it as close as you can without binding. I basically push it hard together, and back it off very slighty, then try and turn the spur a full rotation. If it binds somewhere (often it seems to be tighter in one part) then open the gap slightly more, and try again. If it gets to the point where one side of the spur is very close, near binding, and the other side is really loose, the choose a mid ground so the gears will get worn into each other :P (not common, only usually a problem with cheaply made crap).

I think a common technique might be to put a bit of paper in there and push it hard together, tighten everything up, then pull the paper out. maybe double layer the paper if that doesnt work.