No such luck on the magnet. I checked it after doing a search on internal card problems. It is firmly in place, and besides, I can get the card function to return with a reboot without touching the back.

Although this gives me an interesting piece of evidence. With my problem, the card IS NOT greyed out! So, it looks like the card is mounted but it shows that it is empty and I get an error if I try to write to it.

Next time I'm going to try removing the back cover briefly to remount the card without a reboot to see if that works.