I've been a long term Mini enthusiast and have an Elf and a 1977 1275GT which I'm restoring from scratch. I am having an unexpected problem with the brakes and seek advice: It has an early, simple diagonal split system and I've replaced everything with completely new parts: New GMC167 tandem master cylinder. Silicone brake fluid. When I try to bleed the system, the N/S front to O/S rear circuit bleeds normally but the o/s front to N/s rear gets no pressure at either nipple, just gravity fed odd drip. This happens no matter how much I repeatedly or rapidly pump the brake pedal and I get no pressure from the pedal either. The totally new parts are fitted exactly as per the old circuitry. (The only thing I reused is the failure switch screwed into the master cylinder body to replace the blanking bolt it came with because of apparent non-availability of this part now). There are no leaks along the pipes or from the new cylinders or calipers. Any thoughts or ideas please??