Breaking/broken parts are inevitable. Even simple handling and/or assembly can break a part that's structurally weak or has inherent molding flaws, like bubbles in the molded part, or in my recent blog post, directionality of the molded plastic. The latter is not so much of a problem until it comes to sanding; each time you complain about having a nub mark at an odd position which makes progressive sanding an entire part necessary, you can attribute it to directionality.
In my case, I break a lot of parts especially during test fits and modifications. Sometimes, a part is just too darn weak, or, I'm just too darn impatient. When I break a part though, I no longer fret because I've learned a few trick on how to fix them.
So here's one, strangely enough, not by me, but, something I can relate to nonetheless because it's all too familiar.
DarkWorkx sent me these two pictures:
Referencing the picture above, drill a lateral hole on the base of the peg/ball joint and on the hip ideally the connective parts that broke so you can align them easily later on. Make sure that the hole is just big enough to fit a piece of runner or round beam SNUGLY (it should hardly move even without cementing them together). Next apply enough cement to the holes, plug the core in, and align the parts together using the other side as a guide. If you also have extra thin cement, use that to saturate the surface of the join. Let cure for AT LEAST 24 hours or more preferably. Work on something else if you're impatient.
I guarantee, this method works since I have employed it a few times on broken MG groins, joints and pegs extension modifications as well (where I had to combine ABS with PS plastics). If done correctly, the repaired part should be stronger in normal handling situations than it was factory made.
Here are a few examples.
Hi-Nu groin peg fix:
Angelus Leg Extension and Wrist Joint fix:
Chimera Neck Extension: