There's usually a copper washer between the center nut and the lid, and a flat rubber gasket around the perimeter of the canister under the lid. Those are notorious for getting misaligned and leaking.
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!