One thing you may want to check. These come RTF... when they glue in the Hinge on the control surfaces, sometimes there is extra CA that cakes up the movement. You should be able to remote the clevis and check to see what the range of motion is on the control surfaces. If it seems like it doesn't want to move much... look closely and see where the binding is. Most likely you will see an over use of CA. Dig out the crust between the surfaces and that should free it up a bit. Make plenty sure you don't tear or damage the hinge itself.

Just a thought, seen it before on another RTF.