The brass nipples on my '76's carb were also notorious for either pulling free or leaking fuel slightly.  I was given the advice to JB Weld them in place, so I tried that and it hasn't leaked or pulled out since.  Just make sure the JB Weld doesn't flow into the carb and plug up any orifices...

Adam
Flathead Valley, MT, USA
1976 CT90 - Shiny Orange
1973 CT70 K3 - Candy Riviera Blue
1970 CT70 HK0 - Candy Blue Green (project)
1979 Z50R - Tahitian Red (project)
1964 CT200 - Scarlet Red (project + extras)
1968 CL175 K0 - Dark Blue (project)
1978 NC50 - Pal Green (project)
1982 & 1983 CT110s - Monza Red (projects + extras)