I had a similar thing happen on my old C kite. Although the entire valve didnt fall off, there was a hole around the base of the valve i suppose it was almost completely off. Anyway, the way i fixed it was with a bit of lilo camping sleeping bed repair patch stuff (i think any material that is sort of water proof will do the job) and a whole lotta silicone from a corking gun. After it had cured it still felt sticky so a bit of talcum powder on it did the trick. Then just slip it back into the LE and your done.

It worked surprisingly well, and never had a problem with it again.

Hope that helps.

look for the 'u-stick' stick on replacement valves. damn deflate valves are more trouble than they are worth

Err, not my bladder. That`s beyond repair, too much alcohol.