If the tester is just leaking from the vent valve, isn't that just a standard Shraeder valve? I have the HF gage kit but forgot. If so, a regular car/bike one will work, but maybe yours just needs to be tightened. If endemic, maybe Ho on the night shift was lazy about tightening them.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans