After restoring the AOM driver back to its original power cable, the ISS would not lock and kept oscillating. The servo control voltage kept varying between ~0.2V and ~0.6V, meaning that the amount of diffracted light requested was varying from one extreme to another. I looked at the diffracted spot and all I noticed was the intensity of the diffracted order seemed fairly constant. The input RF was measured with an oscilloscope to be ~410 mVrms, which as I recall is not enough. I opened up the AOM driver and the +15V voltage regulator was no longer supplying 15V. The spare AOM driver has been installed for the time being. Whilst hardware-wise things are in place, I will have to wait until the computer maintenance tasks are completed before being able to test the ISS again. The external laser shutter - ie the one located in the high power oscillator - is closed for now, and the watchdogs have been turned off.