One of the details about the leadout wire a lot of people don't consider is the leadout wire's effect on the bellcrank. If the wire is simply threaded through the bellcrank holes it's going to have to wear against the bellcrank right? And the bellcrank is going to wear against the wire. And if the model lives a long and fruitful life, either the wire or the bellcrank is going to get chewed. Not only that, but as they wear they can develop a stickiness or roughness. So....

If you didn't bush the wire, then the smaller the wire the more apt it is to wear, and break, especially if it's so small that it shows kinks where it's bent through the bellcrank hole.

Is your's bushed? Did it kink when you made up the system?

BTW, don't sweat cutting out a section of your sheeting. Cut one piece out that spans the center section. The wing has open bays right? Go from open bay to open bay, and replacing the balsa will be very easy since you won't have to match up but two seams, and they're along the grain.

And BTW, it's dead simple and easy to make epoxy filled bushings for your leadout at the bellcrank holes. And any decent stunter, no matter how small, will be a bid smoother flying with those contact points bushed.

Hope this helps.