Heyo his happens to me a a lot. What exactly did you take apart? Make sure you put it back together tight and secure. The crash
MAY have jostled it a little bit. If it still grinds that means that your transfer gear/spur Gear is shot. That's the blueish one in your gear box.
![](http://www.xmodsource.com/forum/images/smilies/icon_wink.gif)
if thats broken then I suggest investing in a stage 2 motor.
-XMU