Brake M/C Rebuild woes.....

["Ken.Strauss" <Ken.Strauss@pscmail.ps.net>]

     Does anyone have experience rebuilding a master cylinder on an late 
     MGB.
     
     I got a rebuild kit from Vic/Brit for the M/C and tried it this 
     weekend.   I can't get the pressure differential mechanism out of the 
     master cylinder.  Haynes says "just hook up an air hose and blow it 
     out"  but all this does is blow air out all the other holes in the 
     unit!!!
     
     Any help would be greatly appreciated.
     
     ken.strauss@pscmail.ps.net
     1980 MGB