Geoff Clare wrote:

I'm starting to think that maybe I'm wrong about the pilot light
staying lit. If the pilot light went out, it seems plausible that
the control box would turn off the main gas valve and immediately
re-light the pilot light. The short time delay between the valve
starting to close and the click when it closes could mean that the
click masks the sound of the spark that lights the pilot light.

You might want to start a new thread - I only looked in as I was looking
for an old post somewhere.

I don't think a pilot lights would relight anywhere near that quickly
after they've been running, too much polluted air round them.

Assuming you've checked the gas valve connections, next stop is the
thermocouple. It could be signs of one that's getting a bit marginal.

--
Scott