My understanding is he polishes on the hammer as well (contact points). Then places a friction reducer on it, as well as in the hole for the tension pin, for the spring mount.
I asked if the friction reducer should also be on the hammer pivot pin (the shaft that goes through and locks), but received no response on that.
I've got a spare one from a subcompact that I am trying to learn how and what he does, to do it and install in one of my subcompacts.