after only 35 years of ownership of my spit 1500 i have done everything you can do to maintain and sort out the breaks on this car .i know them inside out and upside down .today i put new rear flexi break pipes on, the originals were looking a bit tired after 40 years .i have now spent over 2 hrs trying to bleed the system with no success i just get bubbles galore for ever and ever .having never had this problem before i need some advise as to probable cause and any ideas on how to rectify this. thanks