Left speaker broken in a 24" iMac

Have you checked in system preferences that the sound hasn't somehow set itself to come only from the right speaker, there is a slider allowing you to change it from left to right.

Not sure how much it would cost to change, although getting to actual speaker is pretty simple if you can source a new one, just follow any instructions that get you into the machine like changing a hard drive and it'll strip it down enough.

Mostly it's just a case of removing the glass using suckers or a bit of tape stuck to one edge, then undoing the screws that are revealed after removing the glass, then aluminium frame then lifts off, revealing the speakers.

Hi,
if you're good with your hands, there are service manuals available out there, everything is explained in detail, and replacing a speaker is quite easy. I've done it recently on my 20" 2,16ghz intel.
The right speaker was buzzing badly, it sounds like new now. And I still have the left one (they come in pairs) just in case.

Look on the web for "imac 24" service manual", there should be something.

Good luck.

Interesting, my left speaker was dead out of the box.