I have a 56 88 and it set for a time and now no brakes. The vacuum is working - the master sylinder is insider the unit. I have not found a rebuild kit so have not pulled the unit. Any suggestions either as to the suspected problem and/or getting a rebuilt kit. thanks, Gene

 

I got my parts from Kanter auto products 1-800-526-1096

 

Kanter has parts try filling with fluid & bleeding