I was told by several Amazon tech people that, after repairing my old Kindle 2 by installing a new motherboard, that the motherboard an the radio chip are a matched pair and that I therefore wouldn't be able to register my repaired Kindle. I then contacted the company that sold me the new motherboard who said that it was a matter of using an domestic 3G module with a domestic motherboard, and that you couldn't mix the domestic motherboard with the international 3G. Because they didn't have any international motherboards in stock they sent me a new 3G module for free.

Amazon wouldn't tell me that, though. They wanted me to buy a new device rather than repair an old one. I have since backed up all of my Amazon purchased books on Calibre, and plan to buy a lot more books from Google when I get my new Lenovo IdeaPad.