Ok - an update for my own post. It appears they *are* soldered normally. Mine must have been just barely soldered at all and completely disappeared when it broke free.
I fixed my player by putting a small amount of solder on each contact spot on the board. Then putting the button over it.. then carefully heating the little metal wing that covered the soldered area. After a brief second, the solder softened up and covered the wing enough that the button was soldered in place and now works perfectly. It takes a steady hand and a good eye - but it works.
Alright, as happens to many MP3 player owners.. the tiny little volume up button broke loose of its circuit board (on the Sansa Clip+). I managed to take it apart without destroying it.. found the loose volume up button. I can put the button back in place and click it where it will work properly and increase the volume.
The problem I have is how to fasten the button in place. It seems awfully tiny to solder it in place.. and I see no evidence that it was ever soldered before. I tried super glue and while it does hold it in its spot - it seems that the glue spreads around and causes the button to stop working. I then have to try to carefully scrape the excess glue off of the circuit board to get it working again.
So - what other options do I have? Anyone know how they're attatched normally?
(and, yes, I do realize that the Sansa Clip+ players are very inexpensive and I could just go buy another one. I would still like to fix this one if possible).