The faulty regulator which turned out to be only a bad o-ring in the regulator itself, has been repaired, reinstalled, and air is flowing again. I unlocked the valves with Chandra watching the vacuum screen in the control room.
While I was repairing the regulator, Kyle was ordering a couple of new regulators for spares. 

Chandra and I also replaced the check valves on the corner station instrument air compressor.