In his effusive review of the new ToyBiz Marvel Legends Series 3 movie Daredevil today, yo mentioned that he used "glue surgery" (a rather silly and imprecise name, as long as you're asking me) to fix a loose ankle. But what, exactly, did that mean?
If you have an action figure with a loose point of articulation, pour some super glue into the joint, then keep moving it back and forth until the glue has fully dried. This handily thickens up the interior surfaces, creating more friction between them and a tighter fit. Just make sure you don't stop flexing it while the glue is wet, or it will stick in place.