Hi there....I just finished installing 3 Totos in my house and even broke a tank doing it. Here's is what I've found.....Toto doesn't give you all the parts you need. You need to buy one of those "tank repair kits" that have rubber washers that you install IN the tank and UNDER the tank. In other words the tank is "sandwiched" between two rubber washers and a nut right under the tank. Now, your bolts are tightened and you put the whole unit through the bowl and I once again use a rubber washer, then the metal washer and then a WING NUT to tighten the bowl to the tank. Make sure you use pipe joint compound on the rubber washers and the tank-to-bowl gasket. Then, you shouldn't have any leaks and yes you will probably end up with a little movement of the tank resting on the bowl. I've decided it's just a defect in the china. If the "rock" of the tank is a little much, I'd put a bead of silicone around the tank and let that be a cushioning to the bowl which will also give it some strength!! Good luck!!