Bad booster? Replaced master, no power brakes, vacuum leak

[Junkie]

A couple weeks ago my master went bad and started pushing fluid from the front reservoir to the rear. This morning I replaced the master, only to find that I don't have power brakes.

I noticed a hissing, pinched the hose from check valve to booster and hissing stops/idle drops.

Is there any chance I could have bumped something that I need to fix, or do I need a new booster?

[bd]

If the 11/32" vacuum hose is not perforated and the check valve grommet is not torn and the check valve is not cracked/broken, replace the booster.  It probably has a torn diaphragm.

[Junkie]

is there anything I should know about replacing a booster? never had one off before

when I pinch the line between the check valve and the booster the hissing stops, so I'm pretty sure it isn't the check valve

should I replace the check valve anyway?

[bd]

The check valve is located on the booster.  The vacuum hose runs between the intake manifold and the check valve.  Post the year, make, model and a pic of what you are working on.