For a while now, I've been having a great deal of trouble getting my jetbook to read any SD cards 1GB or 2GB. I found that by holding the SD card down as far as it would travel, it would read the card.
I disassembled the jetbook today and took a look at the SD card slot. It's soldered well and looks okay. Except ... the space between the SD card and the bottom of the SD slot were too large.
Being the tinker freak that I am. I took a very tiny screwdriver and made 7 small indentations along the bottom of SD card cage. Very tiny but enough to hold the SD card all the way at the bottom of the SD slot without the clicker activating. If you have one, you know what I mean, you press the card down and it makes a click noise when it locks.
After I did that, I was able to do the firmware update and everything works perfectly.
My jetbook has a bad SD slot. I'd like to have the slot replaced but I fear I have tinkered too much!
If anyone else has the intermittent SD card reading problem, this will probably fix it at least temporarily if you want to do a firmware update.