Are they solid copper washers? If yes all you have to do is, re-anneal them. To do that hang them on a bent coat hanger, heat them with a propane torch until cherry red and let cool. That makes them "dead-soft" again and brings the sealing back to them. I have been doing it for years on solid copper head gaskets gas and oil lines on antique motorcycles. Have to it is really hard to find parts for 1913 Indian MC's

David Fritzsche
1990 Ex-Cab V-6,5-speed, with a few mods
04.5 CTD Dodge 2500 Ram--Tow Rig
Roseville, CA

"Serenity through Sobriety"