Did you Print indivdual segment and oriented to vertically? then probably break off ball's neck. try it as horizontaly with automatic supports.
Did you print Set that 5Segments and with custom support succesfully and in attempt put together then splited horizontaly? then cut off or grind off ball's top and bottom a bit then try put together.
when i build this snake i exprience that spliting too, and i thought fix that by end of assemble.
The Filped Mesh's in ball soket is intended enhance ball strength by build more perimeter inside ball (see layer view mod inside ball)