 When those pop up, that center cylinder is usually solid plastic. It's a black plastic thing that pops up and then it starts spraying around in its pattern. And then when the water shuts off, it drops down again. Well, sometimes that part that pops up, it can get so scratched up from dirt and debris that it just doesn't allow it to rotate it right. And they've taken care of that by making some of those that have a stainless steel