Re: Lost tiny bolt
here is a couple of ways to replace the missing part.
take off the clutch plate take it to a store that sells metric threaded fasteners and match up the missing part.
Or drill it and tap for an American fastener. You can even drill the hole for the locking bolt/screw in a different place and leave the original hole alone just mark it so you don't try to install an anerican fastener in it,a simple center punch mark next to the metric threaded hole would work for a mark.