1991 Ford Escort cranks but doesn't start

I have a 1991 Ford Escort, 1.9 L, automatic trans, with 249,300 miles on it. I stopped the car last week, and an hour later went to start it and it would not crank over. I tried boosting the battery with another running vehicle, still no go. I put a test light on the starter positive terminal, and it lit up ok. I thought it might be the solenoid, so I had the ignition key in the CRANK position and put a test light on the small solenoid wire, and it lit up ok. I then removed the starter and replaced it with a new one. I bench tested the new one and it ran fine. After installing it I tried to start again, and nothing happened. I went back to the ignition, removed the wire connectors from the key cyclinder, they looked ok, so I reinstalled them. The key is somewhat worn, but it does turn the ignition all the way to the CRANK position. I tried moved the gear selector from PARK to NEUTRAL and tried, still no luck. Thinking it was the Neutral Switch on the automatic transmission, I placed the gear selector in REVERSE and the backup lights came on. I did not test the Neutral Switch yet. With a fully charged battery, new starter and power to the starter solenoid, could it be this switch? When I first try to crank it over I hear 1 click from the starter solenoid engaging, but the motor does not turn over. I put a socket on the crankshaft pulley, and the motor turned over easily, so its not a mechanical problem. I am completely out of ideas what do you suggest?

thanks,
Clint