I was able to get the second player working by cloning the working one. I had to do a device clone, not a volume clone. On my Mac, I created the disk image (.dmg file) using Disk Utility, but was only able to write the image file to the second device using a program called CopyCatX, since Disk Utility seemed to only allow writing to a volume, not an entire device. (It may be that I was doing something wrong, however.)
In any case, dd showed the contents of the first 64 sectors of the two devices to be the same after cloning. Whether or not it's the change in these sectors that allows the second player to work, or if there was another change that is not visible, I'm not sure. And it would still be useful to know how to get a player working if you don't have another one to clone.
Last edited by aarons510; 06-12-2010 at 10:21 AM.
Reason: minor typo corrected