…And, hold that finishing nail with long needle nose pliers and not in your hand.
I have one of these pots I haven't used in years because of leaks. I'm thinking to empty it, pull the rod, and maybe lap it lightly with some valve lapping compound to improve the seal.
As for cleaning, I'm also thinking to see what Wipe Out's NO-LEAD will do. Leaving it in a bore for an hour turns all the metal fouling to an easily patched away crumbly black substance. It might loosen up a lead-bearing clog, as well.