If the brake pedal is very hard and not easy to depress when the vehicle is running then yes you have a servo fault. Might be that the pipe linking servo to inlet manifold is blocked or split if in doubt replace pipe first and try again.
If on the other hand the pedal spongy and goes to the floor then you might have air in the system. Try this with your foot on the brake and car running depress the pedal with hard foot pressure keep the foot on the brake and test to see if the pedal goes nearly to the floor if there is air in the system the pedal will slowly go to the floor.
In any case check all wheels on inside make sure there are no tale tale leaks from wheel hubs. Usually if it is a wheel cylinder you will see brake fluid on the hub and most probably on the wheel.
Next make sure that the brake reservoir is filled to maximum mark if you find that it has dropped and you find no leaks then you may need a set of Brake pads or Brake shoes or both.
Obviously once the pads and shoes or both are replaced the reservoir will go back up to level. If in any doubt take your vehicle to an approved mechanic to inspect the system. Hope this helps.
carlito corway
June 2008