Yea.. Got it. But not via OTA. I took a slightly scary approach. Via ADB and the android SDK
It actually isn't to bad if you are willing to do a bit of research, and didn't take long once I had everything I needed. Which was basically USB drivers for the nexus 10, the Android SDK with adb tools, 7 zip, and the images.
Download the 4.3 images Direct from Google here Factory Images
https://developers.google.com/android/nexus/images#instructions
Basically I followed the directions from this post on
XDA and just substituted the file names that were there for the nexus 7 with the file names in the nexus 10 image.
The thing that drove me crazy was that the image file is compressed several times. Even in formats that 7 zip didn't recognize. I had to right click on the file and force 7 zip to open it to get it to show the next level in the compressed file.
If anyone tries it good luck. This does have some risk so don't yell at me if you brick your tablet.
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Oh yea that will wipe the device to so be ready for that. I would suggest backing up with something like helium first.