a simple check to see if your servo is working
engine off,press your brake pedal,start your engine keeping the pedal pressed,if the pedal goes down a few millimeteres once started then its ok.
OR press the pedal a few times with the engine running and hold it there switch the engine off and press a couple more times and the pedal should gradually become harder,if this fails you should go straight out and buy a mk2 GTI 8V
Good advice there.......apart from the last bit of course

Made me laugh though