I've had an ongoing seat problem with one of my Drake soft close seats. It kept moving to one side. The bolts were 3/8 diameter while the holes were over 1/2. I finally had enough and purchased a couple nylon spacers. 3/8" inside diameter and a slightly larger than 1/2" outside diameter. I think they were .725 or something. Anyway, cut them 3/8" long and place them in the holes. Works great.
