Hi.

Sorry to hear about your problems with your second hand purchase :

I would try and work out a way to just put a bolt on to lock the wing spar in place....just in case : my thoughts would be to try and duplicate what T/F have done in the other wing half ie: drill a hole in the other wing,exactly over where the spare slides in ( so that a bolt will push down onto the top of the spare to lock it in ). This bolt can be held in the wing using a "blind-nut" / "captive-nut" in reverse from the surface of the wing,so that the spikes will be sticking into the wing surface,you could use a thin bit of ply to ensure good strength and epoxy the "nut" to the ply,then the ply to the wing surface after removing some covering material.
The bolt then threads throught the captive nut and onto the top of the spar to lock it in.

Hope that the above makes sense.

For the U/C.........just use some metal wheel collets ( with the correct threaded bolts) of the correct dia of the U/C wire..........just the same job.

These are what you need for the door "flaps" on the U/C,see pic: Material is a "piano-wire" approx dia 1.01mm / 0.040"...have you got the plastic plates as in the photo..?

Kind regards..............Nick (UK).