As Patrick surmised in alog 23788, the lockloss at ~2240 pst Saturday, this lockloss came about after the Tidal signals ultimately driving HEPI hit its ISC imposed limit of 250um about 75 minutes prior.

The attached 1 day trend shows the HPI-ETMX_ISCMON hitting the 250 limit imposed just upstream at the HPI-ETMX_ISCINF filter.  HEPI has no problem opening up this relief and I'm sure I should have done so already.

This amount of "Tide" is not real though so something else must be driving the requirement.  I suspect an initial acquisition offset that ends up at HEPI or temperature changes either at the ends or in the PSL area?  Attached too is a 30 day trend of the 'tidal' drives to the End HEPIs.  One other lockloss is attributable to this limit being reached on 10 November.