I've had mine for well over a year now... never had any problems. If you got the new kit, I understand it comes with both the tunnel chassis and the new flat chassis. Perhaps your friend is overtightening the dif case and stripping them out? I love the S3, its a great and underrated buggy. Easy to work on, tweak and drive. Parts are easy to come by, when/if I actually manage to break something. The only thing I don't like is that the bodies do not fit the extended chassis very well.