By a 14 year olds strength and would it snap in 3 tries?
Check the rubber belt is non-conducting. Some types of rubber have added material to make them slightly conductive. Use a multimeter if you have one. I don't know why you are using 2 bowls - only 1 is needed. Just have 1 at the top, at least for testing. You need many thin 'points' at the top and bottom to transfer charge; these are called 'brushes'; a brush is often made from wire mesh, cut so there are a row of sharp points the full width of the belt. Make sure the brushes are just touching the belt, or have only a tiny gap. Make sure the bottom brush is well earthed. Good luck!
You don't have to kill them, you have to use missiles to get them away from you and out of the way long enough so that you can lock onto MB then a cutscene will ensue
