Bruce, your right about the 6mm pads, just got back from the bike shop and all they had was 6mm. Might try the other shop.
I did manage to get a thinner washer though.
The existing prop washer is around 2.5mm thick and the new washer is 1mm even, so that will help, that and a drop of loctite I think.
Not the best idea I know, but better than a prop coming loose at 10,000 RPM.

This whole experience is not much fun at all
The Sunday maiden isn't looking good[]