I had the same issue with a 20 3/4" Regina. But mine seemed to be that the star wheels were wore more than the comb tips. Being 111 years old, both are probably worn down enough to not reproduce the treble notes..
Pity that you forgot to mention the disc number. but I think I could see it. I have only number/title-identified 230 of the largest Regina discs. MELODY: 0:03 Reg68cm-4083? Traviata: Brindisi = Drinking song / La Traviata: Libiamo ne' lieti calici [Alfredo, tenor] / Trinklied = Auf, schlürfet in durstigen Zügen / Traviata: Chanson bachique / Den vilseförda: Dryckesvisa [waltz]. - 1853, Guiseppe Verdi (1813-1931).
