OK... like other have said Redcat is not the best truck out there and probably not a good choice for a beginner. I have a couple of their cars and for me they're fine but i've been doing this for 25 yrs. Out of the box my Ground Pounder worked perfect but after 6 months or so I ran into the same problem you're describing. I lost all range and the truck wouldn't respond to any of my input. I also managed to chip a couple of teeth off the Spur gear. Why the motor is attached to the chassis and not the gearbox I'll never understand but whatever.

One thing I noticed when the truck did run properly is I never used the goofy 4 wheel steering so I made some links and locked the rear wheels and simply swapped in an old traxxas receiver and radio and it's worked great ever since. I also found out that the traxxas 32P spur gear will fit the gearbox with a little work so that fixed the gear mesh problem on my truck as well. If you really don't want the GP i'm sure someone will take it off you hands. For someone new to the hobby a Traxxas Slash, Pede or Rustler is a better choice.