While investigating high particle counts at End-X, found the vacuum pump came up in reverse direction after the power outage.I reset the pump and adjusted the by-pass air. Ran Zero Count and Flow test, and all appears OK. 

   Checked End-Y. Found and fixed the same problem. Checked the CS as well. Since it is on a 3-phase circuit the pump did not restart in reverse. 

   Looking into making the power recovery of the vacuum pumps more robust.