Manually install Android 4.2.1 on the "takju" version of the Samsung GALAXY Nexus7
Manually installing Android 4.2.1 is no harder than lather, rinse, repeat. You download the specific file meant for the "takju" model, reboot your phone to let it recover, and sideload the update and it is all done but the shouting, And if you want to wait for the OTA version to reveal itself, well that is just dandy too.
We should point out that if you didn't purchase your Samsung GALAXY Nexus from the Google Play Store, but flashed the "takju" factory image on the handset, this manual update should work for you as well.
source: Android 4.2.1 via Xda,GALAXYNexusForum