All i can say is I sheared both sides of the spars. I have always read the kit's manual 3 or more times through and found that exact thing out the 2nd time through. The Extra .60 is a great kit but dont install Ca hinges, and when you go to make the trailing edges of the kit use a thick piece of balsa for the hinge mounts and install hinge points. I just had Ca hinges fail and I emailed Gp and told me to Send them to their Tech department for examination. Strange but you might have a bad batch too. Get a good set of robart hinge points or nylon hinges. Go with the dual elevator setup and make sure you have a strong elevator setup, Mine without me even looking came with defective wood and half my elevator flew off in a base leg turn. Beware, build light but also build it strong. You might even guy wire the tail section. Since your already at the wing, you must have already done the elvator and rudder, I was hoping I could tell you to make aerodynamic counterbalaces like the rudder already has. They really cut down on Vib. Good Luck and hope you dont go through any trouble with the kit. Its a great kit, take your time. my 2 cents