Installed a small piece of insulation at the output end of the reference cavity.  That helps plug the large hole in the thermal insulation.

The ambient temperature sensor is now mounted to a post behind the reference cavity periscope.

Prior to entering the enclosure I encountered some problems turning on the HEPA FFUs for the laser room.  Normally one would hear
them kicking on but I didn't on the first two attempts.

Both air conditioning units stopped whilst I was in the enclosure.  With the same error message as the other day
CHECK           E4              01
   00           ERROR CODE
                1C
Hitting the ON button reset things.  The control panel on the outside displayed TEMP SWITCH OFF.