I don't own one of these models, but from what I can see from the posted photos is that it would appear that the wing joiner was not glued to the main spar....that's why you have that lateral "slice" taken out of the bottom of the wing sheeting. If that's the case, then the wing joiner was merely aligning the wing halves and added no structural integrity to the entire wing.

Glassing the center section of a wing---- I'd do it for a balsa sheeted foam core wing but not neccesarily for a built up wing.

Saginaw......Cool! 1/2 of my genetics are from the Owendale/Cass City area