That sounds like the exact same size as the end of a decking screw.

For my Yamaha TW200, I got one decking screw (which is a perfect fit - available from most hardware stores) and screwed it into a small piece of wood. You then just hold that and the spanner and Bob's yer uncle.

Yes, you can do it with pliers, but (for a special like me) this way makes it heaps easier. :thumbup1: