hi
the servo helps to make it easier to push brakes ,try this ,take off the breather from the servo to the inlet and start the engine and then put your foot on the brake and see how hard it is to brake the vacum generated in the engine which attaches to the sevo helps to draw it in to help braking effort less work but i will replace the servo with new one to give me somthink to do saturday because it looksa bit tatty
mark2