1. With the engine off, depress the brake pedal several times until it stops and hold it in this position.
2. Start the engine. With the brake booster working normally, the pedal should move forward a little more.
3. If the pedal does not go down, then check: is the low-pressure hose coming from the intake pipe or, accordingly, from the vacuum pump to the brake booster, tight; is the vacuum pump working; is the return valve of the low pressure hose, the rubber ring between the main brake cylinder and the brake booster working; whether the booster diaphragm and air filter on the brake booster tappet are damaged.
4. To check the return valve, remove the low pressure hose from the brake booster.
5. A normally functioning valve can be purged, but air cannot be drawn through it.
6. For replacement of the damaged rubber ring between the main brake cylinder and the amplifier of a brake drive remove the main brake cylinder.
7. Optional air filter can be replaced. To do this, remove the old air filter with a wire hook from the push rod of the brake booster. Cut the new filter to the middle and put it around the pusher in place. Make sure that the filter around the tappet is fitted tightly, otherwise unfiltered air may enter the brake booster.
8. A defective brake booster should be replaced. The amplifier is not repaired.