got 3 ways of fixing 1 replace valve again 2 wrap some insulation tape around bung to make it bigger 3 grind a small piece of wood and stick it in the bung so it makes the outside diameter bigger (this is the best way imo)

stick the bung in hot water then stretch it by sticking a pen inside until it fits snugly.

Sweet - Cheers for the tips, will try the hot water and pen method, followed by tape if that doesn't work.

To Chris if its the stopper just grab a new one or you can dip the valve end in boiling water which will make the valve shrink and make the stopper tighter, the main reason valves and stopper become poor fitting is that they arnt separated after a session,so when you pack up pull the stopper out of inflate and deflated valves it prolongs the valves lifespan, if your struggling I've a few spares you can have 4 free just email me your adress and ill send you a couple cheers , oh if you go the boiling water method be careful not to dip the valve fully into the water as it can delaminate the valve