I also picked up a similar flip dot display from Joe @ Rollsigngallery. Same company display (Luminator) but a different model. I have a total of six display units allowing for 30 characters. Eventually it will be an (awesome) clock.
I found the patent MAGNETIC DISPLAY ENERGIZATION SYSTEM AND METHOD HAVING IMAGE DATA COMPARISON. for Gulton Industries (the division that owns Luminator) that explains a lot about how the logic for these signs works; it even recaps the internal software specs. That was pretty useful.
But Claude - I was planning on using a bunch of shift registers and H-bridges to control the row/column voltages. There are also some lines dedicated to doing row blanking (setting an entire column to black). However, I haven't figured out which junction points on the PCB correspond to each row and column. Can you show or explain which ones you are using for your proof of concept?