I have manual brakes now.

[Zachry302]

Hello, I was re roofing a house the other day and upon driving to the job site I heard vacuum hissing/leaking out and my brake pedal no longer had the x10 force to stop the truck as before. My question is are the check valves bad or is it the diaphragm inside the vacuum reservoir? What I believe are my check valves sit below the driver sheet metal floor pan and the plastic housing is cracked; although I don’t hear or feel vacuum hissing/leaking out. The check valves look like they have a perforated end cap of some sort. Today I went to the dump and made it back although I can’t stop on a dime anymore any help would be appreciated.

1974 C60 350 V8