Well, tried everything I could think of, saved my waypoints onto a card and deleted everything off both units and the interlink. Status shows all 0's and it will briefly show both units unlocked and with 0's - then it starts toggling back and forth, connected then disconnect. It will do this with either unit plugged in alone. Tried switching ports, power on/off in every imaginable combination. No dice, and not amused.
Contemplated seriously sitting the interlink on a fence post and taking vengeance on it with my 44, but luckily (for it)
it was too dark for an adequate sight picture by the time I reached that level of frustration. But there is always tomorrow.