However, if the buckle or the adjusting device is part of the attachment, the buckle or adjusting device shall be tested with the attachment, in accordance with 2.7.6.2, except in the case of retractors with a return pulley or guide at the upright. where a retractor is tested as an adjusting device, the length of strap remaining wound on the reel shall be the length resulting from locking with the strap unwound as close as possible to full length less 450 mm.