It is some time now that my handbrake failed to pass the Harvey's test, and gradually the handbrake performance became not acceptable. So this afternoon i dived under the rear of my P6 for some manual caliper adjustment. The LH caliper responded as one would expect, and the movement of the quadrant was shortened significantly. However, the RH one was a different story, because i could turn the quadrant through its full travel without any effect to the pad movement. I didn't had the chance to check if the foot brake works at all in this caliper, and i can't think of what might have happened inside the caliper, but for sure i have to take this caliper out, and have some spare caliper guts available. I am sure it is not down to any assembly problem at the time of the last rebuild, because both rear brakes and handbrake worked properly for years and the car was passing the equivalent MOT inspection.