Sound problem with iBook

[Loki]

I have an iBook G4 and it seems to have developed a fault recently. Its only playing sound out of the left internal speaker. At first I thought this was a hardware problem i.e. the Right speaker. However when I plugin headphones or external speakers I still only get sound via the left channel.

Is this a hardware problem or a software config problem

 

[Loki]

Thanks.

I am still learning my way around Mac OS.