While bringing the IFO to Low Noise lock for the first time today, the ISC_LOCK Guardian got stuck at ENGAGE_ISS_2ND_LOOP.  After unsuccessfully trying to re-request NOMINAL_LOW_NOISE in hopes that it would unstick itself, I asked JeffK if he had any ideas.  We dug into the ISC_LOCK code, which led us to the IMC_LOCK Guardian where the ISS requests live.  Not seeing anything obvious, we ran out of ideas and called Sheila (the on-call commissioner).  She suggested that we request a lower state in the IMC_LOCK Guarding (PREPARE_ISS).  I did so, and with ISC_LOCK still requesting ISS_ON in the IMC_LOCK Guardian, it ran through without issue.  Take-away message: if ISC_LOCK gets stuck in ENGAGE_ISS_2ND_LOOP again, open IMC_LOCK (still in Managed) and request PREPARE_ISS.