Thanks for the replies, guys.

Unfortunately I should have posted this in the Powerbook forum - not sure if it can be moved there (Moderators ?)

I'd like to just be able to swap the chip if possible, since my "donor" powerbook's sound doesn't work - only one speaker works).

I'm happy to strip it down, having done so on the "donor" whilst trying to get both speakers working, when I fitted new speakers etc, so I'm pretty sure it's a problem on the 1GHz's board, or with the sound jack. Either way, swapping out the mainboard, whilst giving me 1Ghz, would leave me with mono sound

I'll look into the overclock option...