>>1390172>Why is it leaking air at the base of the stem and not at the top??because the valve is connected to the tube using epoxy and sometimes that will come unsealed and you will lose air at that point, it is a quite common problem. You can repair it with epoxy yourself from a flat kit but long term just buy another tube. For the gerry-rigged repair just put on a rubber glove and smear the epoxy around the base of the stem where it connects to the valve.