Thanks to Will Simpkins who beckoned to me as I was passing by from a coffee break, the relocated MOURNING WARBLER was seen again and very visible.
Just inside the woods edge at the horse trail that curves around, specifically at the "DO NOT ENTER" traffic signs next to the horse trail, the male MOURNING WARBLER stuck around inside under the canopy , most of the time feeding in an elm sapling. At times it would come down , but mostly the birders saw it about 15 feet up on average.
Will was about to give up , heading out along that horse trail when he heard the call /song note and the rest is history.
So for this skulker species, it pays to know the call even if its the only one you learn ( and then again there is Kentucky Warbler, there is...)
see the map https://mapsengine.google.com/map/edit?mid=zxPoHx468byE.kHEpRNDGlmt8
hear the call http://www.allaboutbirds.org/guide/mourning_warbler/sounds