Left speakers working only!`

Are you sure you have a stereo to RCA cable plugged properly into the Airport express? If you plug in head phones is it in stereo? Are you playing stereo music?

I am suddenly having the same problem: AirPort Express is working on the left channel only. Somebody tell me if they can think of another explanation here, but I've come to the conclusion that, in my case, it's got to be a bad Airport Express. My network consists of an Airport Extreme and two Airport Expresses connected in two different rooms to different sound systems. One Airport Express still works: I've got stereo out of two speakers. But one suddenly doesn't. For the one that doesn't; I'm hearing the left channel only. I've eliminated all the variables I can think of: the amp and speakers work fine with other source material (CDs, etc.); when I unplug the stereo miniplug connected to the "bad" Airport Express and connect it to my IPOD instead, I've got stereo and both speakers. I've even tried two different computers, a Mac and a PC, and whether either is streaming an ITunes song to the "bad" AirPort Express, I've still only got one channel. The funny thing is, I was about to convert my entire CD Library and buy a third Airport Express -- but if the technology isn't reliable, I'm having second thoughts....

UPDATE: I just swaped the Airport Expresses from one room to the other, leaving everything else the same. Now the room that had left-channel-only, bad Airport Express, has stereo out of two speakers with the "good" Airport Express. And the room that previously had both speakers working now -- with the "bad" Airport Express, has only one channel out of one speaker. I even tried resetting the Airport Express -- no luck. Bad hardware.... apparently a hundred bucks down the drain...

Powerbook, MacBook Pro, others Mac OS X (10.4.8)

Do you have a spare digital optical input on something you can use with the "bad" airport express with? It's probably just the analog output that is bad. There is a digital optical output in the same plug that probably still works. I actually use that for my airport express, and it works fine.

Yes, my friend bought an Aiport with Airtunes in March and now it's only transmitting on left channel.