I have a table clock with the same mechanism (12104), which unfortunately stopped working. I still have the instructions, though.
Quote:
"
An automatic night-time silencer mechanism is conveniently built into your clock so that the chime-melody and hourly strike do not sound at night between 11:00 P.M. and 5:45 A.M. If you wish to silence the chime-melody and the strike completely at all times, then turn the volume control knob as far as it goes to the "min" position.
"
No instructions on how to configure it for different hours. Seems that's not possible...
If someone can tell me where I can find a working 12104 mechanism I would greatly appreciate it.
Francisco
May 2023