Hi Matt;
Your reply made me stop and think this through a bit more - the forest for the trees thing... I rechecked and discovered no ground signal was coming from the ECM (green wire) to operate the solenoid. Upon removing the ECM and opening it up I found a fried 3.9ohm resistor just off the 5th pin that connects to the green wire - hence the problem. Have made repairs and things seem to be working fine now. I miss the days of points and carburetors...
Thanks so much for your help and clarity on this one!