I have a problem with the clutch pedal that is stuck to the floor, you can pull it back by hand, put as soon as you press it, it stays on the floor, also when you do this you can hear air hissing from the direction of the clutch master cylinder. I've tried to source a new master cylinder without any luck - does any one know where i can get one (Part No 358 721 401 - VAG don't make supply this any more) or of another fix ?