Hi guys i am having a brake problem on my other car, but could apply to a locost, the symptom is the brake pedal travels further but it is intermitant. i have checked the NRV from the manifold to the servo and it seems ok plus the system has not been disturbed so i don,t think it could be air. i am at a loss any ideas. cheers davef.

It sounds like air in the system, or a small piece of debris which has got itself to a place where it shouldn't be - this can take a long time to show itself.

Master cylinder seals could be worn and intermittently turning insideout, best way to check is to peel back the bellows on the back of the cylinder to check for any fluid loss.

Yep it sounds like the master cylinder seals to me. Try applying the brakes gently and slowly with the car parked up if the pedal ends up fully depressed but appears ok when you press it firmly then it sounds favourite.
Dont do what I did and dismiss it as a bit of air and plan to bleed the brakes at weekend. My brakes failed totaly while desending a very steep hill complete with hair pin bend. It was only a nifty bit of driving and the total lack of other cars on the road that saved a disaster.

Hi guys thanks for the responce, it sounds like mark may be right about the lips on the seals folding over intermittantly. will check it out. cheers davef.

Is it a Vectra by any chance?

Hi Hornet no it,s an old Kadett, cheers davef.