I just bought this 49t spur gear and just got it today from towerhobbies. My old one is now bald. Anyways, i replaced it and everything and then i go to run it and i'm doin high speed runs up and down the driveway and notice i have TONS of slipping. I tightened down the slipper the whole way and noticed that there was no spring showin anymore. Finally i looked in the manual and realized that i forgot to take out the washer that was in the old 52t spur gear. I threw that away... I had to search through the trash to get and it and finally got it and took it out and replaced it in the 49t one. FINALLY got it work and then i was floorin it up the driveway and then right when it went to go into second gear it revved to like MAXX and i heard this really loud CRACK. I checked it out and found out i had lost a tooth in my spur gear and then the mesh between the clutch bell and spur gear was really loose. AH!! Back to towerhobbies. I should have checked it!!!