Is that the one channel working via the earphones...If so, then the headphone socket requires changing.
Do both channels work OK on aa docking station?
If not, then it`s a motherboard fault......but most likely it`s going to be the headphone socket. A fiddly job, but can be done. Might be cheaper to buy a used IPOD off Ebay and swop the insides over.(Then resell the bits back on Ebay ...You might even make a profit !)
RegWorts, May 2008