Removing the plug 6 (see fig. 140), remove the gasket 5, take out the piston 10, the spacer sleeve 3, the seal 7, the spring plate 8, the spring and the thrust washer with the sealing ring 2.
Wash the parts with isopropyl alcohol or brake fluid and inspect. The surfaces of the parts must not have visible irregularities. Damaged parts, as well as the seal and O-ring, are replaced. Check the elasticity of the spring: its length in the free state should be 17.8 mm, and under load 7+0,8-0,4 kgf - 9 mm.
During assembly, all parts are lubricated with brake fluid and installed in reverse order.