Save the 4 ch TX and use it for a buddy box I've seen 20 yr old Transmitters which will still work for that. (I've got a 12 to 15 yr old one from a garge sale that I use as a buddy box.) The cost of a flight pack with 4 servos, and the cost of a 4 channel complete system are close to the same. You get a spare charger adn TX battery (and usually more stuff) with the 4 ch system.

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The structural question on the wing... you need an experienced modeler to see that before its covered. If you can't get someone to look it over, you need to redo the fiberglass with epoxy. (I recommend 2 hour epoxy for the fiberglass tape on the wing joint)

The center joint on the wing takes up to 30 times the weiht of the plane in some maneuvers. If you have ANY doubt about its strength... it needs to be fixed. There's usually not much left of the plane if the wing fails at that joint in flight. (And the 5 lb lawn dart can do a LOT of harm if it hits something or someone...)