Wow, does that ever bring back old memories! As kids we always took a small pin with us and if the plug (the old brass headed KLG's from memory) didn't seem to be working we'd take it out and have a look. Usually the coil would be collapsed so the head of the pin got used to drag it back out. Sometimes the coil would be broken so we'd pull the lower bit up until it tangled with the top part and that gave us a circuit again to get the plug glowing for another flight.

Newbies soon learn to use an old plug when running in an engine