Really excited to hear that IMC is back now!!

>> Efficiency of MCe is smaller than yesterday(25.5MHz/V) by a factor of 0.67. It may be because optical gain(calibration factor) was smaller(if so, the actual efficiencies are larger).
It seems unlikey that the actuator efficiency of MCe suspension varies by a factor of ~0.7 day by day. This is probably due to the change of the optical gain, as you implied.
To remove the effect of the change of the optical gain, it would be nicer to inject sine signal to the suspension immediately after injecting sine signal to the laser PZT, since we already have the efficency of the PZT, which should be more stable.