Replacing the brake booster on an 04 element. Ordered a reman part and hooked up the vacuum line before installing it. I expected to see it pull a 20mmhg vacuum and bring in the push rod but it doesn't move. A slight sucking dound is heard near tge push rod. This is the second part from Autozone. Can you not check it unmounted? Was hoping to set the push rod clearance this way.