you will need a new main board for your tv, I would use a surround sound system and mute the tv, if you don't use the mute settings in the user menu, then you will get feedback through the speakers,
The right speaker on my DLP set started dropping out and only the left channel will work.This is also true for the external audio out.The right channel pops on randomly and then goes off again.It is not a cable problem as it is the same with the external and internal right channel.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic