[Kiddcade]

Get some Petroleum Jelly and a hot craft-glue gun.

You're going to want to treat the neck ball liberally with the petroleum jelly, then set it aside for a minute and get your craft-glue gun. Once it's heated up, fill the socket about 3/4 of the way with craft glue and while it's still hot, stick the neck joint into it. Let it dry this way. the Petroleum Jelly acts as a mold release and the glue takes on the shape of the balljoint, makes a nice little vacuum-seal around it and it's soft enough to have a bit of "give"

Afterwards. clean up. if any glue is sticking out the bottom of the socket just cut it off with a small blade. you'll be good to go.