My Take

In 15 airplanes I built I used the DuBro Fuel Valve. Only in one did I encounter a Air Leak.

http://www3.towerhobbies.com/cgi-bin...&I=LXD745&P=ML

If I would reseat the Valve it would stop the leak.

Dubro offers a rebuid kit for the large Valves I am not sure about the smaller ones.

http://www3.towerhobbies.com/cgi-bin...&I=LXD687&P=ML

Personally If I needed to I would continue to build and use these Valves in projects.

Ian