Help with a shoulder joint fix?!

Thanks to both of you. As you can see, I tryed sculpy and a metal stem and that didn't ever take hold. The second idea was something I was debating as well as the first and feel more confadint now that others have voiced this.
Saddly, in order to do what I wanted to I need this arm and this shoulder joint. Cause I need this torso. That octagonal
Little nub is what I need to fit back in. Thanks so much to both of you. I have been stressing about this stupid thing.
Fixing this stuff is usually easy for me? No matter what I do nothing seems to work? I'll touch back when I get it fixed or, give up :] again much thanks.

If you can get a smaller on diameter screw, I have a solution. Put a little bit of superglue on the screw and screw it half way into the arm. After the glue dries, cut the head off of the screw, apply super glue to the exposed portion of the screw and screw the peg onto it. Once everything is dried and tight, you can reattach the arm to the body.

Yeah I'd go for the screws, just make sure you have the perfect size, personally I'd try drilling straight through the broken off bit, and making a small indent in the end that the screw head would sit in, just big enough for the screw head to sit flush with the end of the peg. I'd then apply a small amount of superglue to the end of the screw and screw it into the shoulder disc then move the joint around for about 2 minutes to stop the glue from sticking it. Not sure if you've tried this or even if it would work but it's what I'd do. Or you could just swap it with one from another figure.