Some interesting stuff over at TFW as people try to see what is wrong and if there is a way to avoid a problem. there seems to be a miss assembly (to go along with the questionable plastic) :
My friend, who's copy was cracked right out of the box, brought his over, and I took a look.
At first, nothing seemed different, but then I took off the ratchet piece., and it was definitely miss assembled at the factory. The diecast hip bar has a square peg. The purple ratchet has a square hole. His, however, was put on wrong, somehow not lining up the square to square.
You can see the ratchet was put on rotated 45 degrees from where it should, and forced down enough that it smashed the plastic down. Those corners at the green arrow shouldn't be there, and were created by forcing the part down over diecast hip joint. You can see the smashed plastic at the red arrows.
Here's another angle without the arrows so you can see the smashed down plastic a little better.
And compared to how it should look
So what does this do? Well that damaged ratchet doesn't sit down as far as it should, since there's now smashed plastic in they way of it sitting properly. I'd also guess the internal circular section is pushed outward slightly too. All of which, in turn, will create extra tension and stress when two crotch have were screwed, too tightly, together, causing the crack. You can see below that the affected ratchet, on the right side in this picture, does sit slightly further out than the one of the left.
