[slyalfa]

if the ABS pump goes the pedal gets rock hard. if you have never driven a non-power break car you will likly crash. the power needed on the pedal is a lot so much that you pull up on the stering wheel. the softeening pedal sound like seals to me. I had the happen and I just changed the master with a used one and that was that. I still have the old one. but I did not find a seal kit for the master last time I looked.
if the accumulator is all the way bad when you hit the breaks the pedel will be hard and you will feel the pump kick on and the pedel pump up and the breaks will come on slow. the light will flick on and flick off very fast any time you change the pedal force and the light and motor will kick on and off

the yellow ABS will stay on with almost any fault and as a rule need to have the key switched off and on to reset it