Drum roll please....
...and the Golden Phone goes to...wait for it...C5Z!

I have no idea why simply copying the flex button programming from ext101 to ext108 worked. Sure enough, all 8 CO's are now programmed and working. However, I still have not tried to save any programming changes directly to ext108. Don't want to press my luck.

Thanks again to all. There's no way that I would not have posted anything that was helpful or even not helpful - any CORRECT information is helpful even if it does not fix the problem. The type of assistance provided here can't be found in a manual or a FAQ. We used to help one another much more years ago. I guess I'll have to help some of my old buddies bait their hooks when I'm fortunate enough to join them off the grid.

I did run into one more issue with the TDA50. I'm starting a new thread, so if you are as good as C5Z, your assistance is greatly appreciated.