Thanks for the pics
. The washer looks to be about .010 thick. Mine is about .032. The flat on the shaft allowed me to use a little thicker shim. When I tightened up the first of the 2 screws on the spiral gear with my shim in place, I don't think a minor difference in thickness matters as the shift of the brushes on the commutator is very small and the machine runs like new.
Rodney