Sometimes general sloppiness in the dowel hole is the problem you can smear a little epoxy in the hole and then file it out to fit the dowel snugly. If the hole is located too far towards the bottom of the bulkhead you might have to cut out a section of the bulkhead and glue in a new one with the hole reposisitioned. You can also fill in the dowel hole in the leading edge and cut a new hole lower on the wing. There are several options available but it's important to have a tight fit between the fuse and the wing.