theres a leak on one of my carbs it looks like its coming from the air mixture screw? what can i do about this

Ooooo that is extremely rare ... you sure its not getting into air box.
Anyway, if certain it is the air screw (yes it is possible though I am yet to see it - however gasoline goes through that passage, so why can it not leak) ... send me $3 and I'll send you a nice pair of those O rings. $2 for mailing it ... I could prolly go a flat envelope and a sheet of paper, so OK make it $1.50. Anyway, its a tiny ass O ring.
Cool.
Buddha.