Today between 8:00 UTC and 9:00 UTC we have done two tests to investigate the issue of the OMC slow shutter with a broken stop.

Stop and start the driver. This did not resolve the issue, the shutter when opening still runs without stopping when arriving to the end. We have stopped it manually after 1 minute.

Replace the driver with a spare, serial number FT4ZNKQD. The configuration of the rotation process was updated with the new serial number. The issue remained the same. The translation stage of the shutter still doesn't stop when closing.

All these actions were performed with DET_MAIN in pause and the interferometer in single bounce.

In conclusion the driver is not the issue, and probably the in-vacuum translation stage has one of the two stops that is broken.