All of the reference line tubing was insulated between 0800-0840 this morning.

Based on one spectrum, it doesn't look like this has made much of a difference.  Does this mean <yet> something else is going on to cause these Pref fluctuations?

Tonight we should receive another Pref sensor.  Tomorrow I intend to use it as the new Pref sensor and configure my current Pref sensor (the 11b 202BG) exactly as done in CHATS.  This should allow a comparison of a single sensor ala CHATS to the AHATS system measurements.