I actually went ahead and removed the actuator (~$55 per our host, shipped from Germany) and I did confirm that it was bad, and for the reason I described. I admit I am not that smart- I do commercial HVAC and this is a common issue for old pneumatic actuators, and they exhibit the same symptoms.
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As soon as little vacuum gets pulled, the diaphragm exposes this tear and the vacuum is lost, so both solenoids go CLICK CLICK.