60gig version is worth repairing. I have heard stories about people paying for repair and getting a slim back. (granted they are internet stories and can't be wholly trusted)
I would not want to risk this. I would rather replace the drive myself and replace it again if it needs another replacement. I could honestly care less if Sony says they won't work on it if I open it. Usually the only failure is the Drive or the heat sink getting too dusty.