sounds like one of my first bashing experiences....i was a super newb to r/c and i kept wanting to ride wheelies, and i was also slamming it into reverse then forward (you didnt mean to, but i did lol ) anways thats when my first experience came from changing out my first differental

i sure did pop that cherry
i would take it apart and check it... never know whats wrong till you just start taking stuff apart