Well, it’s important to use the right tool for the job. Using my new Saleae, I found out MUCH more about the signals. The first finding is, that using a cheap scope will generate false signals and waste of time 😉
All signals are taken at the ribbon cable that leads right to the head, after any electronics. Here is a photograph of how the pins are mapped to head. Note that I defined the leftmost pin as 1. The printhead contacts are of course reversed, so the top right contact is 1 in my previous numbering. All further numbers refer to the ribbon wires!