Well. One thing that causes it is if the holes in the mounting braket and motor mount are too large and the landing gear wire flops around inside of it. it should be a close fit just free enough to not have any friction or binding. The landing gear wire should not move side to side or front and back unless you force it enough to flex the wire.

Two, too small or a poorly heat treated landing gear wire. It flexes too easily and tends to bend and stay bent too easily. You have to get a new one.
Three, if the plane is too large or heavy for the landing gear wire, then you need to go up a size larger in wire thickness. The Fults gear works really good too.

Four as mentioned already, the nose wheel only turns a little bit from side to side, 10 to 15 degrees.

Five, the nose wheel hole in the axle is too large or routed out or worn out, allowing the wheel to flop around from side to side. Also you usually need a wheel retaining collar on both sides of the wheel, so that it doesn't move from side to side too much.