While waiting for the PCBs, I worked on the clock source. As the PCB did not change from my prototype, I only had to create a small part in tinkercad.
Perfect ;-) - Now a little sanding and cleaning (and optionally some acetone-polishing (ABS print)) is missing.
With this design, the pulse will be 1/2 turn HIGH and 1/2 LOW. With one turn per second it will generate one falling edge for the CD4040 every second.