Según XDA si se hace por CWM hay que borrar la carpeta recovery.
Method 1 - CWM recovery installed
1) Download the correct update for your build on to your computer;
2) Open the archive and delete the recovery folder;
3) Copy the file to /sdcard on your device;
4) Reboot into CWM;
5) Select "install zip from sdcard";
6) Select "choose zip from sdcard";
7) Select the update the you just copied to your device;
8) Wait until it completes. Reboot. Done.
