If you find anything, I'm dying to hear about it!
It'll be a while until I get to open mine up and stick in an audio cable.
PS: Under the heading of, "You made me look, again," I just checked one of my other boxes. Same thing. It also has one of my "older" drives in there, and the jack doesn't work.
I am begining to think it's Win XP, however. This other drive, I'm certain, worked before. But... there is one thing I noticed on the two machines I tried: Both play fine using the regular speakers and not the headphones, but the unusual thing is that the drive light comes on, goes off, comes on, goes off..... like it's being buffered into the system. It's not playing (reading) constantly like a music CD does / should. Hence my suspection it's an XP setting somewhere!
TwoRails