Place the car on a lift or inspection ditch, clean the pressure regulator and its drive parts from dirt. Visual inspection to make sure that the pressure regulator and its drive parts are not damaged, there is no fluid leakage, plug 24 (see fig. 82) recessed into the hole of the body by 1...2 mm, there is no play in the connection of the earring 11 (see fig. 81) with elastic lever 10 and bracket pin 15. Ask an assistant to press the brake pedal. Piston 2 (see fig. 82) at the same time, it should move out of the housing by 1.6... 2.4 mm, compressing the leaf spring 7 (see fig. 81) until it stops in the lever 5. The lever 5, overcoming the force from the elastic lever 10, will rotate relative to the pin 4.
Non-compliance with the listed requirements, lack of piston movement, as well as its insufficient or excessive stroke indicate a malfunction of the regulator or its actuator. In this case, you should contact the service station for repair or replacement of defective parts or assemblies.