It may not seem like much but we replaced all the interior doorknobs. The ones we replaced have been in place since I was born and were always problematic. The locking mechanism was a small, easy to miss, pin. It was relatively easy to push the pin into lock position when closing the door, thus locking you in. The upstairs bathroom was the worst because the pin was sometimes a little finicky to disengage. There is nothing like being locked in a bathroom to get your blood pressure up. In the upstairs bathroom it was never a good idea to put any kind of lotion on your hands before assuring the door was not locked! I'm not sure why we took so long to fix the problem, but visitors will now need to look for exhilaration somewhere other than the upstairs bathroom.