J-B Weld will hold it on if anything will, but my guess is that it won't stay fixed.
The way the factory put it together evidently wasn't strong enough, since it did break off. Even if the J-B Weld holds that break together, the next hard knock will just break it somewhere else. So after you've put it back together, you'll have to be very careful with it.
Tip: If the nature of the break and the surrounding parts permits it, you might try supplementing the J-B Weld with a couple of tiny self-tapping screws (you can pilfer these out of junk point-and-shoot cameras) or pins cut from stiff wire (drill snug-fitting shallow holes in both mating pieces, fill holes with J-B Weld, insert pins, wipe off excess, then glue the rest of the joint and assemble.)
The screws or pins reinforce the joint against shearing or bending. J-B Weld is very strong in tension (against a straight pull) but a shearing (crossways) or bending force can break the joint because it only has to break a little of it at a time. The screws or pins reinforce the joint mechanically against bending or shearing, making the initial break harder to start.
