You are using Gen 1 Xmods. Ok, you need to take the differential gear off. Open three screws on the flat side, open the cover, you will see three baby gears inside (Sorry I don't know how to call it). Apply glue on those gears then immediately put the cover back in place. While the glue is still hot, try to put the joint shaft (
http://www.atomicmods.com/ProductInf...roductid=10081) into the center hole to ensure it fits. Sometime when you open up the gear, the center plate slidely changes position, you may not notice it but it results seriously that you can't put the joint shaft back in. Ok, that's how it can be done. People used to stuff tissue paper (in the baby gear position) instead of glueing. I've never tried this, but you should try this before glueing it. :P Post results after you done. Enjoy!