>>10547248maybe pop a little thin joint saver tape or even scotch tape over the ball. The crack will probably only get worse though. The other anon is correct in making your first priority trying to secure a replacement or replacement part from the retailer.
After that, there are a few things you could try to seal that gap but I don't know how well they would work.
Tiny zip tie around the socket rim to tighten it? Heat shrink for the same purpose?
MAYBE as a last resort, some kind of plastic cement, but you've got to be very careful in applying it or you'll just melt everything
maybe just don't buy mafex figures
