I am working on dry fitting everything in my tub. I mounted the seat brackets in the holes that were predrilled from Aqualu. The pitch between the mounts is 500mm (19 9/16"), but the pitch between the mounting holes on the seats is 515mm (20 3/16"). Has anyone else run into this issue? I'm not sure how to make up the 5/8" offset I am seeing in the mounting holes.