Eproms are quite robust really but Nelly has had a few that were dead on arrival. JHP say it is something to do with the scanning equipment the post office use. If you are fitting it yourself all you need to do is earth yourself first by touching a metal appliance that is plugged into the mains (doesnt need to be turned on, the earth connection should be okay assuming it isnt double insulated of course). Just make sure you dont bend any of the pins or break the old chip when you are taking it out.