Sadly I haven’t gotten around fixing anything yet. I have been busy with finishing some old projects that I had laying around half finished (See misc). I will see if I can still get warranty on the printer, else I will first fix my old mendel up. If your machine is so good you don’t want to reverse engineer it, it is good news for the printhead quality. It seems more and more likely to me that the printhead actually has shift register on it. There are in total 12 thin traces going to the color, 3 for each color. The black has more lines running to it, making it very likely that the big black head has more than 1 shift register (for speed). I hope to get printing before December, so I can see If my hunch is right.
If you manage to find something interesting on the printers you have right there, I would be more than willing to put more effort towards that printhead. The CN642A was picked based on availability and potential, but when there is already a (partially) hacked printhead out there, The potential for that printhead suddenly rises dramatically. I will let everyone know when I have resumed inkjet experiments.