The little door to our dishwasher's soap dispenser won't open inside during the wash cycle. It stinks, yeah. But it's hardly a reason to go upgrade our kitchen appliances. When your ear buds start to show a little wear, you might decide to buy some fresh ones right away. But when it comes to more expensive items, like dishwashers, we're willing to put up with a lot of small kinks to be able to put off replacing them. So how do you know for sure when it's time for a new one?