1. Remove the passenger backrest.
2. Remove enough staples so that you can peel the seat cover back from the top to expose about half of the foam.
3. Ease the foam away from the plastic backing plate. You will see where there is a groove in the foam where the plastic backing plate should be inserted, however, the backing plate is not installed correctly into the foam.
4. Sparingly apply some contact cement along the edge of the backing plate where it should insert into the foam.
5. Pull the foam around the backing plate, making sure that the backing plate is in the groove in the foam where it should be.
6. Once you are satisfied with the position of the foam on the backing plate, pull the cover back around the foam and re-staple.
7. Re-install the backrest on the bike and the gap will be gone.
If anyone else happens to know of an alternate solution, please
let me know so I can include it at this site.