SA2 cell#5 undulator segment moved at ~09:45AM Fri to 25mm without aparent reason and undulator experts need a ZZ to exchange power supply; FEL instensity dropped from 230uJ to 60uJ s consequence.

RCs are preparing south branch for the iminent ZZ. HED is informed.

**Update: ZZ finished by 12:10; recovered performance and re-started delivery by 13:30.