[Excaliber]

NeedAntiVenom, very good methodical analysis of the starter circuit. But until he get the solenoid to engage it's a bit premature. I doubt the starter is a factor at this point. Low voltage or a bad solenoid is the most likely culprit.

Battery analysis will be difficult without a "load tester", which the starter COULD become, if it would engage!

Couple of shorted cells may STILL read a decent voltage, won't start, won't jump, won't take a good charge, but COULD read a decent voltage with no load on it. I'm betting bad ground and/or bad battery.

Ford solenoids don't generally give you much trouble, but his solenoid could be "really" old and therefore has to be suspect. The internal contacts bad (eaten away after years of starting) or the holding circuit wiring gone bad (age).

The battery in my ERA (6 year old batt) was "borderline" when I got the car. Hard to start when "hot". Then one day, I hit the key and a kind of "thump" from the trunk (where the batt is). The "load" of a hot start blew the battery internally in a split second! No jump, no charge no hope of it coming back. Solenoid click, was all you got!