Yahoo Music Unlimited
It was time for my monthly "license renewal" of the music on my portable player (Sandisk m260). I plug the m260 into the computer and start Yahoo Music Unlimited (YMU). Through the magic of USB, the player shows up as a device in YMU and I push the "Syncrhonize" button. A while later, I get the message that my portable device does not have enough space left. Apparently YMU does not understand "Synchronize". I have perhaps 400 songs on my player, with 2.1GB used/1.6GB free and perhaps 405 songs in YMU. YMU seems to think it needs to re-add the 400 songs and there isn't enough room to do that, but of course there is enough room to add the new songs. I try various things, including removing all the songs on my playlist, which just creates licensing problems, but no solution.
Therefore, I send email to Yahoo support and they respond quickly (as they often do) with a fairly irrelevant answer indicating that they have not read my email at all (also fairly typical). The back and forth has begun.
But the reason for this post is that I found the answer to my original question - and it is quite unusual. If you simply want to update your licenses, connect to YMU and start playing some song with a license - e.g. one a song in "My Music". While that song is playing, plug in your portable. The licenses will get updated through some magic.
At this point, I can't figure out what Synchronize does. If anyone knows, please post!
Some further notes:
* Make sure the player is in MTP (Music Transfer Protocol), not MSC - by using auto-detect on the Sansa series.
* When plugging in the device, choose "Add Music..." although you don't need to add any.