1978 CX500 "The Grub", 1983 GL650I "Nimbus"
I normally flip over a crush washer when I reuse it.Minor damage can be scuffed off on a piece of 400 paper on the bench top, then anneal. Don't quench.
Also, an odd thing about copper. Both quenching and slow cooling result in an annealed condition. Only work hardening (blows or compression) will harden copper.
As you say, annealing should be last, as sanding might harden the surface.