Hi Tyler and Max,
It can't be this hard to just get a float needle to work.
Max, I wouldn't trust a pressure tester in this situation, only thing I am interested in it testing the [Censored] things with fuel and the only way I can see to do this is to set up a rig with a number of carbs mounted on it and a fuel tank above it and just keep the fuel sitting on the seat for a few days. The Viton tip can swell a bit once it is subjected to fuel so at least being in the fuel it means I should be able to fit and know it won't leak in 2 days time.