Some may come as a complete mechanism with laser as an option and others the laser replaced individually but both will require to desolder a link on the laser circuit board before use as these are static sensitive devices. Just a reminder that this link will have to be removed first if you decide to replace but avoid handling the laser and at the very least grasp the metal taps in the kitchen before to reduce the risk of destroying or reducing life of the new unit with static charge if a static wrist band unavailable.
sparky, April 2006