Mine has those too and they are a pain. The wire wants to "squirt" out when I tighten the screw down. Best way I've found to get around the problem is wrap the wire completely around the screw in a clockwise manner. That usually does the trick unless I'm using over 29 awg wire then bets are off....lolI learned something from this thread also! Mine has the rounded screws, so that explains why I have trouble!