I've run the truck a couple times now and found that tire size actually contributes to this. When you have a larger tire, you have to raise the shock collar to compensate for the higher ride height and this can cause the spring to become loose as a stiff spring requires less compression. A softer spring needs more compression so it would be less likely to happen with a softer spring. I have spoken to another sc6 owner who did come across the same thing also. I ran the truck anyway and after 6 races there has been no issue with the spring falling out but I did pay attention to tire size and got it to a minimum. Starting to think it is normal with box set up. Three tires I tried out were AKA Typo (worst, large diameter) Proline Ions (better, slight smaller diameter) Panther Slicks (best, slightly smaller diameter again). If you look at the tires, AKA's are rounded, Ions are less rounded and the slicks were the flatest of the 3. Running on indoor clay. Hope that helps.