I increased the PRCL2 gain that is set in lownoise length control from 1.0 to 1.4 to increase the overall PRCL loop gain by 40%. We have been seeing locklosses with 11 Hz oscillations that are probably due to marginal stability in PRCL. I changed line 5577 of the ISC_LOCK guardian, saved, and loaded. Ibrahim will post an alog with more info and open loop gain plots.