I've had my 2wd Torment for a while, and I recently replaced its stock motor with a brand new brushless one. The first run went well, but when I took it out for a second the next day, I encountered a significant problem. For some odd reason, my left rear axle just decides to completely lock up. It feels rigid and refuses to budge at all, while the right rear axle can still spin when turned by hand, but doesn't feel as smooth as it used to be. If I were to run the motor, the right axle budges a tiny bit but the left one just stays still, immobilizing the car. I also hear an unpleasant, high-pitched grinding sound. Since I'm just an inexperienced guy in this hobby, my best guess is that there is something wrong with the rear differential. I am wondering what could have possibly caused this, and where the problem is. I would also like to know how I could fix this. Thanks in advance!