I got a tip from the Airhead list that solved my Leaky Bing carb.
I had changed the floats and needles and replaced my filter from the tank, but the darn Bing would still leak and leave a puddle on the ground or on my boot.
The fellow suggested taking a Q-tip and Brasso the seat. Sure enough, I did that and it doesn't leak a drop now. I brasso'd the seat til I saw a shiny ring all the way around. I wore out two Q-tips before I saw 360 degrees of shiny.
I had always thought Bing meant leak in German. Glad I have this one solved.