I may fire up an old iMac and see if the M10 might connect with an earlier operating system.
I fired up a very old Mac, an iBook running 10.3.9, and it worked! The Internal Memory mounted on the computer, with the M10 screen no longer flashing when connected.
So I can still download the digital files, and this basically keeps the M10 in service, (as well as the iBook, thus demonstrating to my wife the great benefit of never throwing anything out ...).
Sebastian is probably correct about the USB controller, that something is wrong to not enable it to connect to a newer software.
Thanks dyneq and Sebastian for your help.