In 1851, Linus Yale Jr. patented the door lock; by 1852, the lock was sticking and was hard to turn. That winter it froze solid, and Yale was locked out; in 1853, he broke his first door key, trying to turn his now-very-sticky lock. Today, little has changed. While locks have improved, time, dirt and inside goo still gum things up and sometimes keep Yale's great little invention from doing what it's supposed to do. Rub keys with a soft lead pencil to transfer graphite into the lock mechanism or use powdered graphite from the hardware store. But don't use lubricating oil. It can hold dirt and make locks even harder to operate over time. And that's the On The House tip for today.