[Big-Foot]

How are you annealing the copper washers?

I hang them on a length of wire, heat them with a propane torch for a bit (30 seconds or so) and then quench them in a cold can of icewater..

I also put just a thing smear of anti-seize on the threads of the banjo before I tighten them. Not torque spec but just using a regular hand wrench I get them reasonably tight.