I always recommend putting plumbers grease on the new cartridge. Anywhere you have O-rings, you want to use a silicone-based grease. And especially if you have an older home like this, the buildup of minerals can actually leave little hard particles, and when you shove in the new cartridge, you can actually nick this, and I've had it happen in the past where I didn't grease it up, you'll actually get a nick and it will leak. So the grease does a couple of things. It helps protect and waterproof these O-rings, and then it helps slide it in much easier. And you would not want to use Vaseline or anything petroleum-based because it will actually damage the O-rings, anything rubber. So use a good quality plumbers grease on everything, and it will help you slide it in and help protect the O-rings. So when we install the new cartridge, we're going to be holding it in with this retaining clip, and these two ears, these two extensions here, the clip grows right around it. So we're going to have to make sure that we put the new one in, where these two tabs are on the top and the bottom in this case, because the clip goes down around it. So all I'm going to do is just push it straight in, and it's good to, actually when you're putting it in, make sure the stem is pulled out that way the air passes through it. If the stem were pushed in, it's harder to push in. So the stem is out. Now if you're having a hard time pushing it in, you can also use that tool, put it on here and tap it in gently.