68 911 Clicking when trying to start

I'm having fun. I have a 1968 911 with a 2,4S/901 drivetrain which delivers only a dreaded clicking sound when attempting ignition. The battery in service when the problem first surfaced was 3y old so I replaced it and the new one checks out fine. The car had this issue 5 months ago and I was able to get it started and drive it back to the house about two hours later without issue*; the problem again presented itself immediately after shutdown. It does not roll except in neutral. *There was a multitude of potential fixes occuring at the same time during the issue's first appearance so what actually "fixed" it was not readily apparent. The clutch, starter, tranny and related components have all been rebuilt or replaced within the last 18 months. If I wasn't working nearly 90h/week I would tear down and diagnose but as it is I don't have time for much else besides sending up a flare. Thanks in advance for any ideas.

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This post was auto-generated based upon a question asked on our tech article page here: Porsche 911 Starter System Troubleshooting | 911 (1965-89) - 930 Turbo (1975-89) | Pelican Parts DIY Maintenance Article

[Casey at Pelican Parts]

Haha you ARE having fun! Most of the time this issue is caused by a bad ground at the gearbox to body, or by bad ground straps at the batteries. Also check to make sure that the ignition switch is dry. You may want to buy an electrical portion of the ignition switch (assuming the grounds and starter B+ are good and clean free of corrosion) you can easily unplug the connector and plug in the new one, then turn it with a screwdriver and see if your problem goes away...

- Casey

[T77911S]

that's the first things I would look.

not sure what you mean or why posted about not rolling except in neutral. if the car wont roll except in neutral, make sure the engine can turn over without the car moving. starter should have enough power to move the car if it is acting like it is in gear and clutch out.

check for good power on yellow wire at starter. use a test light. light should be bright. a MM can measure 12v but there is not enough power to pull in the relay due to resistance in circuit.

if you have a car alarm check/remove that. a lot of the time guys will cut into the start wire and install a relay. this just begs for problems with a starting circuit that is already stressed