I saw this fix on Youtube awhile back...wrap a rubber band around the reusable cup filter, just under the lip - below where it opens and closes. It makes a great seal and works! The rubber band can stay on the cup all the time, you just operate like usual (fill the container with coffee, brew, clean) and forget the rubber band is there. I've had it on for a year and it still is holding up just fine. I've also tried a 1/2 inch washer that goes on the top of the reusable coffee container. Both solutions will work just fine on their own, but I kept losing the washer or forgetting to put it on when I brewed. The rubber band worked better only because I didn't have to keep track of a loose part (the washer).