Didn't know this then. But when we had our safety cover installed I should have checked to see if the installers were using a brand new drill bit. Do yourselves a favor and have them show you the bit in the package. I noticed this year when the cover came off that some of the brass pins have a small circular damaged concrete surrounding them. I'm not due for re sealing till next year. I rubbed a candle on these areas and melted with a torch to seal and keep moisture out to reduce further deterioration. Stamped concrete can't be repaired.