Check for corroded traces. They may appear as darkened spots along the trace. Corrosion occurs over time rather than instantly, so if a speck of liquid had touched some exposed copper at some point in the past, today may have been the day it finally ate through.

I have had traces on the front PCB corrode and show intermittent functionality. Simply scraping away at the solder mask and soldering over the corrosion can help. A lot of the time though, the traces are too close together to perform this fix, so some thin wire from one end ot the other works as well.

Start by following the seaker traces back to the amp and then back to the CPU. Use a magnifying glass if one is handy.

Amplifier took a dump or heat expansion weakened a marginal solder joint or caused a broken trace.

I would reflow all of the solder points on the amplifier circuit and see if that helps.

So I recently took my DMG for a ride in my car and it might have been under warm conditions (not wet, not too hot) and when I arrived 3 hours later the speaker wasn't working anymore.

Back home I measured the speaker (still 8 Ohm) and replaced the speaker with a working one from another DMG. Didn't work.

So I thought maybe it was a problem with the headphone jack turning off the speaker without something plugged in, so I resoldered the jack and the sense-cable, still not working.

So I gave up and unsoldered the speaker and cut the white sense-wire.

The question however still remains: what else could be broken that the speaker seems dead when everything else is working as expected?
(the prosound and headphone jack work just fine)

thanks in advance for any ideas,
madpew