Don't use the tool to tighten the lid, you'll only wind up cracking / splitting the lid in half. Only use the tool for loosening a stuck cap. If your jug is leaking, remove the cap and find the speck of grit that it keeping it from sealing. They're a good sealing design, as long as the v-groove and threads are kept clean and undamaged. Once you mash the lid down on a piece of grit in the seal groove, they'll never not leak again. Not without some careful attention to repair the seal damage.