So, turns our there were several issues I had to deal with. Fortunately StreveH (a Steel Soldiers member) came over today, and with his expert help I am back up and running.
The original starter solenoid had a badly corroded disk and the plastic retaining ring on the solenoid shaft was cracked. So instead of trying to fix it, I got a new Onan replacement starter/solenoid combination from DB Electrical. Problem was, after installation, it was drawing an extremely high current the battery connection sparked greatly, and it would not crank. Steve diagnosed it as a connector problem and turns out there was a crack in the ground lug and the battery positive terminal was not tight enough. After replacing one lug, and tightening all the connections, it started without a problem. Of course this was after removing the new starter and bench testing it.
I can't say enough good things about SteveH. He traveled to my home on his day off, was there when I needed help and his knowledge and logical approach enabled the situation to be resolved easily. He is a true gentleman, and now friend. He is the definition of what every friend should be.
Thanks again to all of you for your great advice, and once again to SteveH.
Roger