"1000-grit paper to smooth out the commutator surface"

For those not aware of it... one should not use wet and dry sandpaper... silicone carbide for either Points ( moot on this forum) or electical things like the commutator... one should use flint sandpaper for things like this... non reactive....
and the way to keep it as level as possible is to wrap the sandpaper around it most of the way.... covering all the copper ...