A bit odd. My brakes feel a bit spongy in use, pumping the pedal whilst breaking having very little effect. When stationary however (with the engine running, the booster is working) pumping the brake pedal twice, makes the pedal rock hard, and the brakes much more responsive (when rolling off the hand brake) The brakes work ok, and there is no loss of fluid from the reservoir, and no leaks that I can find.
Thoughts? What have I overlooked?