I love my ThermoQuads, but one of them has a problem

I use JB Weld. You also have to use it on Quadra-Jets in the same place and for the same reason. Also make sure you are using brass floats. My TQ's are still good to go after almost 50 years. The best carb ever made for the street. You have to do quite a bit more to get a Quadra-Jet to get to the same place.