Most Pickett rules (once popular with secondary schools and still in abundance) are aluminum. Remove the slide, wash under warm water, lube with the nearest oil

Most Pickett rules (once popular with secondary schools and still in abundance) are aluminum. Remove the slide, wash under warm water, lube with the nearest oil or fat, reassemble. Takes under a minute. Usually I'd use Vaseline or a silicone lubricant, but expedient lubricants are fine if you'll wash it frequently and aren't trying to make multiple slide moves per minute. The cursor requires a screwdriver if you really gunk it up (I'd be surprised), but it's still pretty easy. You don't need the cursor if you're just using the rule as a single-proportion lookup table, so you could take it off and put it away if it's a problem.