Checking the front brake components (VAZ-21213)

Check all parts carefully, after washing them with warm water and detergent and drying them with a jet of compressed air.

If traces of wear or seizure are found on the pistons and cylinder mirrors, replace the cylinder block with a new one complete with pistons.

Note: In all cases where the piston is removed from the cylinder, it is recommended that the sealing rings in the cylinder block grooves and the dust cap be replaced, which is necessary for satisfactory operation of the system.

Original source is on the resource vazbook