hissing from brake booster
 

Hey guys I have a problem with hissing coming form my brake booster. Its on a 2002 toyota solara though but i figure a brake booster is a brake booster. Im pretty sure its coming from the booster. Whats a way to diagnoise a bad booster? The booster works off of va***m dosent it so im guesing the diaghram is messed up.