[ender]

Its kinda hard to give advice without being able to see whats going on inside the joint. Is it a double ball joint? If so, disassemble the toy as much as possible. Wipe down the male and female joints with a little bit a diluted rubbing alcohol. Once the parts are completely dry, get some super glue and put a small drop on a piece of paper. Finally, take a tooth pick and smear just a tiny dab of super glue all round the surface of the male or female ball joint. You want to have a very thing coat on every surface of the joint that makes contact with the matching piece. Obviously you want to avoid getting any glue into any moving parts that are not disassembled.

You can also pledge floor shine instead of superglue, but I find it to be runny and hard to work with.