Component identification - MELF capacitor? inductor?
Reminds me of tube ceramic caps, but those went the way of the Dodo a long time ago, probably in the 80's...



Although some were adjustable, so maybe that's what the plug was for? A factory trimmed cap?... Quite dubious.



Seems like tubular ceramic caps are still being made but as 3-terminal feedthrough caps. That makes sense for filtering connectors for example.

But that doesn't really answer why they used tubular caps in your tuner when they had MLCCs available...