RE: Knife edge Problem with Yak
Yaks tend to pull to the landing gear at knife edge. The best thing is to make sure it is set up correctly ie cg is right - incidences are right - lateral balance is right - it is trimmed flat and true. Then use the mix to make it fly straight on knife edge and to keep it from rolling out on knife edge.
It takes 2 mixes to make it work rudder to elevator and rudder to aileron
That should get you going straight again