If I remember correctly, I filed a flat spot on the axle so the set screw had something to hold on to and used blue Loctite on the set screw. I called Horizon and told them one of the wheels had fallen off during flight and they sent me a new pair no questions asked. I later found the wheel and put the new set on my old version of the H-9 Cub. As far as not trusting the I know the feeling. Even with the new engine I was a little nervous but after the first flight my feelings have changed for the better. I flew the stuff out of it and it performed flawlessly. If yours runs better now it's probably alright. I think mine was a fluke. If I needed a new 46 size engine I would probably go with a new Evolution. But my plan for the future is a Saito Fa62 on this plane. My old Cub has a Saito Fa56 and it runs fantastic.