I got lucky. Clock (quartz) was working intermittently, running for a few hours, stopping for a few hours, then running again. 12v constant and ground both good at the Bakelite connector. I was prepared to open up the clock and poke around. Luckily before I got into trouble, I found that the 2 tiny nuts holding the white plastic connector onto the back of the clock were not tight. I tightened down those nuts and the clock has been running well since.
In case this helps someone.
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