[Synchro909]

I had a new rotor where the tab on the inside was so small that it slipped on the cam. It took a while on the side of the road to find the issue when the car stopped with so much back firing that it sounded like WW3. It wasn't a matter of wear, the tab was smooth and shiny, just like the rest of the brand new rotor so it was a dud from the factory.
All that said, I have seen them with the spring steel tab where the carbon button in the cap runs has been corroded/worn through and even broken off. I had one break in the middle of the never never one time and had to bend up a new piece out of shim brass to keep me going. It worked so well that I felt a touch of regret when I put a new rotor button on.