We need some more info. When you turn the trim knob, nothing happens? Did you crash and have to replace parts or something? The more detail on how you got to this point, the better.
Well i bought it used and I got it like this. When adjusting the steering trim from Tx, nothing is happening at all. Even if i put another servo to same channel, still nothing. I used my spare traxxas Tx/rx from my revo 3.3 and hook up everything there same results.