Easy - from the chap that makes them
http://paperless.bheeb.ch
Be warned though - Leica have recently modified the X310 laser module and is not compatible.
To all DistoX customers:
ATTENTION:
There seems to be a problem with a newer version of the Disto X310. These new version includes a changed Laser Module which will NOT work with the actual DistoX2 board.
The serial number (on the box and in the battery compartment) seems to start with 0 for old and with 1 for new devices, but this is not confirmed yet.
There a couple of photos illustrating the internals of the two models, but I can't attach them here at mo.
> Upper device: Old version with large Laser module.
> Lower device: New version with smaller Laser module.