Below is a table where we compare the readings on the HWS with different CO2 and RH lensing which ideally should be the same if the amount of CO2 actually corrects the applied amount of ring heaters.  There are a few caveats to the measurement though, the ITMX HWS are particularly sensitive to the beamsplitter's pointing (long term and short term drift).  But what this tells us is that the step down in common lens brought the spherical power closer to the "cold" state before any TCS was applied which maybe makes sense on why the PRC gain got better after Stefan made an adjustment.