That's just it, you don't repair holes in car engines either. It's really an interesting place for a piece to break off. If there were no outside forces that caused it then you should contact Tower and tell them about it. Even without the box you should be able to return it (I save every box and manual for all of my engines. The make a great place to store engines when you're not using them). Like I said, repairs are going to be very difficult to do so that they are permenant. As I said, you can try but don't get your hopes up.

Ken