Bit of a strange question regarding brakes. A friend of mine has a 90 fitted with a 200tdi, Disco front axle and Range Rover 10 spline rear axle. I do most of its maintenance and I have become rather wary of its brakes, even though he never complained about them. He probably got used to them. On the first pump of the pedal, the brakes work fine. If I were to release the pedal partially and pump again, more effort is required to bring the car to a standstill, to the point that it scares me. If the pedal is released totally and pressed again two or three seconds later, full braking power is restored. I have reason to believe that it's a servo fault but don't know what to do to test it. The vacuum pump is working fine. Any ideas?