[Mozzy]

Ok, yes, you def need paddles & a smoother area to run.

What I'd do to find the binding is put the car on it's lid & disconnect the servo arm & move it yourself. Then as you go through the steering mechanism, disconnect things as you go & see if it frees up.

I'd remove ball links from steering knuckles & start there, if it binds, you know where to look.
Good luck.