1. After removing the brake pump, take out the piston from the brake pump, carefully remove the leather cup from the piston push rod, soak the metal part of the brake pump in gasoline for 20 minutes, then take it out, clean the surface, and rinse the inside and outside with brake oil;
2. Soak in brake oil for 20 minutes, clean the leather cup and sealing leather ring with brake oil, carefully put the leather cup back on the push rod, apply brake oil on the surface of the assembled push rod and leather cup, and carefully push it into the master cylinder;
3. Install the sealing leather ring, pull the push rod piston back and forth by hand to check whether there is any jamming. When there is no jamming, fill the brake oil from the oil outlet to push the push rod.
