Just got off the phone with Greg. It is quite clear that the #1 cernox manifold inlet temperature sensor went bad, probably due to radiation damage. As a temporary fix, we turned off that alarm.
Unfortunately, this sensor was also the PID for the 4k JT valve. So, the valve closed, and the HPH turned off. So, we requested beam off to diagnose the problem, turned on the auxiliary HPH, and then Greg coached me through opening the JT valve until returning to an acceptable level. It should be noted that during these changes the scattering chamber vacuum pressure increased slightly. It's since returned to the nominal value.
So, in summary, these two changes were *temporarily* made:
1)The manifold inlet temperature alarm was turned off.
2)Disabled the 4k PID.
Greg will take a look at these in the morning.