Give the tumbler a good hose-down with spray carb cleaner or brake cleaner, followed by a light spray with a silicone-based lube. The oldtime lock lube was graphite powder, but that's fallen out of favor recently for some reason.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!