i have edited the thread because i have just took the brake apart to find that the problem lies with the master piston, i have been able to pull it out with pliers, cleaned the chamber, spring and piston and re greased it, i then put it in and put more fluid in the brake by pulling one of the slevs out and putting the bleed pins in but it still gets jammed in as soon as you push it in..... am i doing something wrong?? ash.