Are your valves leaking and falling off the bladder? When you pump up do you hear leakage around the nozzle particularly if you move the nozzle? Anyway this is a MOST common problem with kites. The older the kite the more likely you are to have this problem sometime.

Plastic Valves (most look like a clear clear PVC) are generally heat formed onto the polyurethane bladders somehow when they are built. This particularly true with the older style kites ie the PVC is melted onto the bladder.

Problems arise particularly in hot Australian conditions when a kite is left in the heat in a hot bag, in a hot car or wet in the sun causing the valves to part from the bladder or partially pull away. And this is particularly prevalent if one pulls too much when pumping or removing the pump nozzle.

Heat effects the formed joint between PVC Nozzle and polyurethane bladder. The formed joint are just stuck together by heat rather than being a good welded joint with the two materials fusing together. The materials are different and not very compatible, it is more like a cold joint and are not resilient from tearing away. This type of weld is dissimilar to the bladder seam welds where the two materials are the same and fused together providing a full strength weld.

I was asked to test an number of glues to re-attach the failed nozzles.

GLUES TRIALED

1. Super Glue (Cyano Acrylate) - FAILED JUST PEELS OFF NO BOND AT ALL
2. Super Glue (Cyano Acrylate) with Kicker- FAILED JUST PEELS OFF NO BOND AT ALL
3. SHOE GOO - FAILED JUST PARTS AND PEELS OFF
4. CONTACT CEMENT SELLEYS - FAILED JUST PEELS OFF but could be used temporary patch 4/10
5. ATTEX HENKEL KRAFTKLEBER TRANSPARENT- WORKS 5/10 but tends to soften and distort plyurethane bladder material due to solvent in glue. Not bad if your desperate and require a quick fix but it wont last!
Hard to buy but this is the glue:

www.henkel-adhesives.com/de/de.html?countryCode=de&BU=cons_crafts&parentredDotUID=0000000KF6,0000000238&redDotUID=000000PLIQ

This list could go on. If anyone could add there good glue experience it would be appreciated.
Most importantly is to test gluing two pieces of bladder material together and pulling joint apart to test joint strength and seeing how glue peels. If it's a good glue joint the bladder material should rip rather than glue joint.

There a lots written on gluing nozzles on this forum but most advice is not worthy of pursuing.
I say this because by nature polyurethane bladder material is virtually impossible to glue with anything. There's a lot to be said about the new stick on type nozzles.

These are the best long term option but at $25ea can be expensive particularly if you need 6 or more.

Try U-Stick
www.u-stick.eu/

or North also have sticky self adhesive valves also.

Read Instructions, they describe how to remove old valve (by heating with hot water! what did I say about heat) cleaning and drying (most important) and laying valve into position. They take practice so don't rush. If you crease or wrinkle the stick-on bit it doesn't come off easily just squeeze out all creases and air leak paths around valve.

CONCLUSION: Use Stick on type valves and don't waste your time with gluing (unless its a temporary patch).