leaking brake valve

Long ago on this board someone showed destructions on "how to" anneal the "new" hard copper washers so they are soft. Do a Google search on anneal. You heat the object and control the cooling time to take out hardness

Many years ago there used to be special little tools for bleeding brakes for the warning switch. You unscrewed the switch, and screwed in the tool, which was a stop device to keep the switch centered. With it stuck, best with two people, you need to crack open the valve fittings to relieve pressure on one side or 't other and bump it back.

Sometimes, just "violently" stabbing the brake pedal a few times will center it