I was cruising along the other day when suddenly my brakes 'went out'.  I had to practically stand on the brakes just to slow the car down.  I parked the car for a few days and drove it again for a few miles around my neighborhood and the brakes worked great.  Is it normal for the brakes to fail completely and then work a few days later?  Do I still have life in the powermaster and just need some maintenance or is it ready to fail for good?   Should I just bite the bullet now and go for the conversion? I am leaning towards the vacuum setup just for ease of installation.