Sheila told me that a couple of OSEMs on the ETMY M0 stage were reading almost zero values. Since ETMY is a key for the upcoming DARM locking, I tried fixing them.
I went down to EY and spent some time trying to understand what is causing it. Finally I found out that this was due to a loose connection at a DB9 connector on a QUAD coil driver (D0902747). Since I was standing in front of the electronics rack with a flat top screw driver in hand, I tightened every DB9 connector which was in the same rack. This should increase a chance to detect gravitational waves.
Some detailed notes