Today Rana pointed out that our FSS slow servo is malfunctioning. It has been for a while that our laser temperature control voltage drifted from 0 to 10.
I looked at FSSSlowServo script that runs at op340m and controls the servo. Script disables the servo when MC transmission is less then FSS_LOCKEDLEVEL. But his value was set to 0.2 probably till reference cavity time.
This means that slow servo was not disabled when MC was unlocked. I changed this value to 7000.
Also I increased integral gain from 0.0350 to 0.215 such that fast control is always in the range 4.5 - 5.5