If your meltin dirty lead in the lee pot , STOP !
I reread ya post & I can`t tell if your smeltin in the lee or in a different STEEL pot , clean ya lead in a different STEEL pot.
I usually flux 3-4 times !!
Empty it completely & clean it out , then take some lappin compound & lap the plunger to the spout , just be sure to lay it at the same angle as it operates .
Then get ya a pair of small visegrip pliers & clamp em on the handle to add weight to the handle .
Anyways this will help but not stop the drip , even the hi end pots drip a little .