Had a similar problem.I used good blind nuts . Shortened the length of the mid screw tube with a dremil to just below the tips of three legs.The three teeth of the blind nut dig in and catch better on the non flat surface of the mount once the screw is tightened .However ,probably one would need to re-tightend the screws once more after a flight or two and then they would do the job .Well in my case ,this kept my 46AX in place for some 20 flights so far.