It mentions it in the installation part of the service manual, but basically when you receive the machine there are two locking pins holding the scanner carriage in place. This stops the unit moving when it's being moved in transport or being lifted at an angle. At a guess the new type of unit are heavier and as such are easier to damage through movement.
IIRC the sp is 4-806-001
Once you've used the code the unit moves slightly. Don't try to scan after doing this, you'll crash the machine on the current firmware
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