If you're very careful and use two pairs of fine-nosed pliers, you can": (a) grip the twisted thread at the base of the loop with one pair (b) grip the ball with the other pair and (c) slowly and gently twist so that the ball just pops out.

I've done it in the past but, if you're wary of risking it, then sell 'em as suggested and just buy a new, correct set.