a couple of things you can check first.
1: you need two vacuum nipple blocks/plugs. i think its the same size/thing as the injector over-flow plug used on the one side.
take off both small vacuum lines off the nipples right near the vac pump. plug these. now check if you have brakes. if so you ve found where the problem is.
several more things. to check a hard line, inspect for breakage, look closely with a light. esp look at the booster connection. here move line some, not too much, see if its broke there.
it can be the master cyl o-ring, or a rusted out booster. an engine listening device, like a stethoscope can hear air rushing. (for any leak, including the hard vac line).