In the past I have run into this a couple times and here is what I was able to do to fix it.

#1 The first thing I would look at is if there is a flat ground onthe nose wheel shaft. If not -- line up the nose wheel and rudder then mark the shaft and grind a flat on the shaft for the set screw to lock onto.

# 2 Check the set screw and make sure it hasn't stripped out the plastic threads in the steering arm. If the threads are stripped you will probably have to replace the arm. I have threaded a larger set screw into a stripped hole and made it work. Another thing I've done is to replace the arm with a Dubro arm # 166. If its stripped and you are very carefull you could also drill out the arm and epoxy a wheel collar into the arm.

My guess is that there isn't a flat spot on the shaft and you have stripped the set screw hole.

Good Luck and ENJOY !!! RED