I just had the idea.
Regarding the broken wing.
I think the way you pin the wood to the workbench may be to blame.
The T shaped pins allow for the pinning without making holes in the wood.
Balsa wood is such fragile medium, any hole made by the pin would make the weak spot. I read a lot of articles about shaping the wood. Modellers always pin the wood on the edges.
Just the observation.
