Locked with 2W input, JAC REFL A LF  signal was constantly railing regardless of the purge air level. Turns out that we were using two stages of 1:10 whitening.

I went to the floor and turned one stage off on the front panel of the RFPD DC interface D1102079 (circuit diagram D1102060) in ISC R1 rack and disabled the corresponding dewhitening filter. I could have disabled both, but with an ND0.5 filter JennieW was installing, this will do the job for now.

I always forget this but gray switch up=1 stage active, middle=2stages, down=0.  I put two labels on the front panel so I don't have to remember.