406. While underway it is noticed that the main air ejector is having a hard time maintaining vacuum in the main condenser. When switching to the standby unit the vacuum returns to normal. Which of the following could be a possible cause?

Switching to the standby air ejector restores normal vacuum, indicating a problem specific to the original ejector. Clogged air ejector nozzle steam strainers restrict motive steam flow, reducing suction and vacuum, which is consistent with the observed symptom.