What do y'all use to clean the metal connectors that go into the bulkhead on either side of the fw?

Unpin one wire at a time, scrub with a fine steel wire brush and CLR from lowes or home depot. Rinse w water and blow out with compressed air. Squeeze the female spade slightly closed so it fits tighter. Rebend the tab that clips it in to the plastic housing. And repin it. Then unpin the next wire and repeat. Do one at a time. It's very slow going, but is the most thorough way to do it.