Solved .... lots of leg work / testing and NOT the expected AC noise one would typically encounter ...
Moved to IOLinc to isolated circuit (known clean from noise ... basically beside the PLM ... still failed
Factory reset the IOLinc / reloaded, failures still present, but random on reload
Checked the power terminals (plug prongs) and electrical plug ... noted some corrosion (typical long term humidity exposure)
Replaced electrical plug, steel wool the IOLinc plug terminals, apply protective electric grease on terminals ...
Working ...
Thanks to all who responded and read my post
