The glass is missing the tension ring, the band is not original. Here is the review of the revision to find: Revision of a caliber Junghans 653.01; Durowe 7526 Junghans Discus
This still unrestored example of a Junghans Discus is fitted with the caliber Durowe 7526/2. The weekday disc would have to be black, also the gilded crown does not fit and must be replaced in the revision.