Is probably okay as the vacuum pump will overcome minor leaks due to the volume of air it can move.

You are correct though that it should go to zero at the stop and in reality should probably hold vacuum forever if brand new...

The test would be to put it on the car (or just attach it) and test it with your cars vacuum supply. Use a tee like the current setup to the tranny and you can read it's bleed characteristics on the tranny side as it is moved from closed (resting, full vacuum) to fully open at the stop (no vacuum).

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'99 S420 - Mommies
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