When replacing brake pads, note the following: Check the protective boot on the brake caliper piston. In case of damage, replace the protective cover. When replacing the seal: check the working surfaces of the piston of the brake cylinder and the brake caliper for contamination (oxidation). Thoroughly clean the piston and brake caliper if dirty and replace the seal. Check brake piston and brake caliper (corrosion, scratches on the surface of the cylinder), if damaged, replace the entire brake caliper. When pushing the brake caliper piston back to its original position: Check how easily the piston is pushed into the brake caliper. If the piston is difficult to press into the brake caliper: check the brake cylinder piston and brake caliper and clean, replace the sealing collar and protective cover. If damaged, replace the entire brake caliper.