OK, so I checked the vacuum hose just before the booster with all vacuum accessories attached. Vacuum at the hose is 20" hg. Plugged the same line and tried to turn the key to shut off engine - engine shuts off fine. So - that leaves the seal b/t the m/c and the booster, or the booster itself. Is there any other diagnostic to descriminate b/t the two? Or should I just get a new booster? I assume any further testing will require the removal of both the m/c and the booster. Please verify. thanks in advance.