This clock is essentially the same as I.D. 507, but instead of the Corbin cylinder marking mechanism it uses a complex mechanism made in Germany. The key is of a complex, contorted  "paracentric" shape carrying a lug particular to each station. When turned in the mechanism, the key first moves the whole marking assembly sidewise to put it in proper alignment, and then depresses the tumbler which pricks the paper chart.

 "Paracentric" Key

 "Paracentric" Marking Mechanism