Thanks for that advice Marco_c,
I will test each individual LED to make sure I don't have a dud matrix. When you say " there were shorts/dry solder joints" in which compoments? I only have mine on a breadboard at this stage but I suppose that even the breadboard or max7219 itself can be faulty. That's the problem there are so many areas for potential mis or non connection. Oh the joys of electronics.
Thanks again for your suggestion BluesBoy.