I had same problem. My Lowes did not have any...but Target did...but same thing when I got home, even with moving the overflow hose. I think the 18qt one I got was some hi rise top thing that was just not happy in the space. I found another version, Ziploc brand, that did fit very nicely and and in fact, the design of the bottom had little "feet" that actually secure it great on the frame. Doesn't slide side to side at all and it has a little gasket for the cover that makes it kind of "waterproof". It was covered with mud the other day, but inside was fine.