Check whether there is no corrosion, wear and damage on internal walls of the cylinder. If necessary replace the cylinder case. The insignificant defects caused by corrosion or foreign particles can be eliminated with grinding of a surface a small emery cloth. If necessary replace the cylinder case. Check whether there is no wear, cracks and damage. If necessary replace the corresponding component. Check whether there is no corrosion, wear and damage on the surface of the piston. If necessary replace the corresponding component. Check whether there is no corrosion, wear and damage on the directing finger and a boot of the directing finger. If necessary replace the corresponding component. Check whether there is no uneven wear, cracks and serious damages on a surface of a brake disk.