Poor Brakes.....

Hi,
my classic has just developed a braking fault, now and again I get excessive pedal travel when applying the brakes. Theres no sign of leakage and the reservoir is still full, it does suffer from slightly warped discs but it always has, I suppose this means it's the master cylinder. What I need to know is if it's feasable to fit a repair kit or would I be better replacing it?

Thanks in advance...............Colin.

hi colin i get this sometimes in my p38 i would like to know too, its a bit scarey when you go to a junction and the pedal nearly goes to the floor , very intermittent usually when warm regards dave