[Daniel, Jenne]

Since the ISS Second Loop board was modified (alog 46317), the old instructions (alog 31262) are no longer accurate. 

• The second loop now "likes" to have the ISS diffracted value at 2.5%.  So, one should adjust the first loop's REFSIGNAL (with the second loop turned off) until the diffracted power is 2.5%.  Then, you should find that if you toggle the second loop on/off, the diffracted power will always settle back to that 2.5% value. 
• If there is a transient when you toggle the second loop, you can then adjust the "AC input offset" in the top left corner of the Second Loop screen.  This seems to be mostly a trial-and-error process; change that offset, toggle the second loop.  If you still have a transient, pick a new offset value and try again.
• The final check (which should just be a confirmation step) is to change the PSL rotation stage to change the power injected into the vacuum, and ensure that there is no transient when the power injected is changed.

The attached figure shows this process. 

• Around -10min you can see that we turned off the second loop, and the diffracted power went down to 1.4%, where it has been sitting for the last few weeks.
• Between -10m and -8min, the REFSIGNAL is adjusted (while the second loop enable switch is off) so that the diffraction value is 2.5%.
• A few toggles of the second loop switch indicate that we have some transients.
• Around -7m the AC_COUPLING_OFFSET is adjusted, interleaved with some second loop enable toggles, until the transient is minimized.
• Around -3min, the power injected to the vacuum was increased to 10W, and we see that there is no transient.  Perhaps lucky but accidental that we have things quite that well tuned.  Around -2 mins the power is lowered back to the nominal 2W, and we lower the power faster than we increase it.  This time, we do see a small transient, but (a) it's pretty small, (b) we're moving the power faster when we go back to the nominal 2W, and (c) we don't really care, since if we're going down to 2W from high power, it means we've already lost lock.