I cobbled together this arrangement to test a booster.
I checked my adapter, using my fingertip as a plug I can quickly and easily pull and hold 25 inches on the gauge.
Now, using it on the booster, after 20 or 30 seconds of vigorous pumping, I can barely get a reading of 6 or 7 inches, which then leaks off over the course of a minute or so.
I have determined the external check valve at my adapter connection is good. And, if I push on the brake plunger rod I can hear the release of the little bit of vacuum I pulled.
I should be able to pull more than 6-7 inches on this thing, right?
Rebuild or replace? Any favorite rebuilders come to mind?