Carb leak on #3 restrictor tube

[charliechicken]

Hello as the story goes had to clean carbs, did just that and replaced all o rings now the issue between the air plenum and the #3 carb where the restrictor tube goes to, that little o ring that sits in the bottom of the carb flange that makes to the air plenum for some reason leaks on #3 i have replaced it a couple times and i get a drip out of it, number 4 is just fine, what am i missing here does someone have the correct size that goes in there i purchased two different kits one from sabre and one from amazon it did not even contain an o ring to go in the its about 6 mm wide and 2mm thick, thanks CC