worked on austin-healeys for over 40 years and never encountered a problem like i have with my granddaughters 71 VW. adjusted brakes and flushed old brake fluid. during test drive realized i was only getting rear brakes. figured bad master cylinder and got new one, bench bled it and bolted it up. same problem. suspected bad master and got another one. still same problem. got one more master and tried again. by now determined i was doing something wrong. followed all the youtube instructions to no avail. back brakes bleed fine and work as should, but no front brakes. run fluid through until absolutely no air. some guy who works on VWs says it takes a long time to bleed them but what do they do at the factory. they can't take days to bleed they system. any help appreciated.