I guess that's why dCS opted to use Esoteric units in their latter transports. But when committed to the 'old stack' there's no other way going about this routine maintenance (I consulted dCS direct). Anyhow, they are quite readily available and not too costly too. A good optical assembly in my experience will last at least 3yrs.
Kctan, if you decide to have just a technician do it, best if you can ask from dCS an instruction sheet (comes with my first factory unit). A clear step by step guide on how to replace them--quite essential actually. As I recalled, there's a solder point which needs to be 'thoroughly cleansed' during the process before your La Scala be able to read any SACDs. Good luck!