[TowerTalk] Lubricating air variable capacitors

[Steve]

I have recently acquired a used Johnson 153-6-1 air variable capacitor 
for use in an antenna tuner. Looks to be in pretty good condition, but 
it does not turn as freely as one would expect.

Is it likely that lubrication would free it up some?

Is it OK to lubricate this type of capacitor? With what? And where?

Thanks.

Steve K8JQ