Ticking sound from car.?

-I have isolated a weird ticking sound to be coming from my brake booster. It can be heard (And only to my knowledge) at idle and as the car is picking up some speed, Which I can't hear it after I am at about 10mph. It's loud at idle and doesn't appear to be affected with engine speed. When I popped the hood and noticed a valve (Hoses connected after the throttle body, Then to valve, then goes somewhere I cant really see but I think the brake booster) it was vibrating alot and had a pulsing sound. When I wiggled it around it was smooth again and seemed to shut the sound up. Now I was told a check valve might be to blame? I am aware of a vacuum leak.my 1996 blazer had a rusty brake boost vacuum reservoir, a noticeable problem at the pedal.

.also,a small vacuum line running from the intake manifold to/4x4,air vent actuators.,

had worn a leak as it rubbed on the master cylinder mount.(fixed with steel tubing)

this set the check engine light and 4x4 did not engage.
sounds like you have diagnosed your problem-fix the vacuum leak