"1. As a preventitive, after disconnecting battery, disconnect, clean, prepare with anti-corrosive zinc compound, and
reconnect all the usual suspects like battery, fat starter stud, chassis/engine strap, generator/regulator, ignition switch,
fuseblock... "

Thats about what I was thinking when I diagnosed my similar problem... But, since the lights ain't fused, nor are they on the ignition switch (unless someone did some creative wiring), It really can't be the fuse block or ignition switch.

In my case, the starter *always* worked, which sorta ruled out the ground straps. I was not the wire from the battery to the starter...rather, the other wires on the same post that provide juice to everything *except* the starter... only one place that can cause that, and its a bad connection on the fat lug on the starter solenoid.

Or a very serious short somewhere else, but that would cause some serious electrical smoke if it went on for more than a split second.

-Matt
I approve this message, even if I may well not have a clue as to what I'm talking about.
--
-Matt '70 145s, '65 1800s, '66 122s wagon, others inc. '53 XK120 FHC