I just got a used vxl 3 slash 2wd. I love thing already but when I put a battery (2s) in it the motor hesitates with a grinding noise and then runs smoothly. I tore the tranny apart to see if it was binding in there but its smooth as silk. I hand turned the motors pinion and it seems clunky anyone know what would cause that?... is it a bad motor? I'm new to brushless so I'm lost. Thanks for the help