Most likely what Alatar said above/below. Like I said, I don't have the figure in hand nor do I have the BvS anymore so I can't verify. My post was going off memory from over a year ago. But, it sounds familiar that a small bit of thread was there to hold it in place. Or it could just need a little force. It could be scary if you've never customized anything before and if you're truly afraid you're going to fudge up your figure, maybe you shouldn't be doing anything to it. I tend to make sure I can fix anything I plan on messing with or at least be aware I'll have to spend some money to replace it if it's beyond repair. But, I've been customizing figures since the original SS Jedi Luke and LOTR figures, so something like a stuck zipper is usually fixable one way or another. If I ever messed up a zipper, I'd just remove it completely and sew up the back, especially if I never intended to remove the suit again anyway.
Alright thanks guys,
Is there a break down pictures for what the bicep and shoulder parts actually look like inside out and separately ? Like a breakdown ?