I sold a set of used B&M 250 blowers several years ago off the board to a guy in CT. I never turned them over to look at the rotors or Teflon strips on the rotor tips. When the purchaser got them he called and told me that the Teflon strip was missing from one rotor. AT my expense I had him ship them to TBS in CA and had both totally rebuilt and shipped back to CT. I did not want to spend the 2.5K but I did. It was the right thing to do.