I've struggled to find this so thought I'd put it together to make things easier. If I've missed it elsewhere then mods, feel free to delete.
I have a UK transformer and I lost loot after the OTA 8.6.5.21 update. Yes, should have checked before applying.
Wasn't able to root with NVFlash so I downloaded
http://www.multiupload.com/X65RBVD2MB the 8.6.6.19 file that was posted by Lizard here
http://forum.xda-developers.com/show...1393953&page=3
I unzipped it until I had the WW_epad-user-8.6.6.19.zip file. I placed this on the root directory of the external SD card and when I rebooted it gave me the option to install.
This installed OK so I just re-ran Razorclaw and sorted. I have superuser back.
Warnings and all. This would seem to be the US update but is working fine on my UK B70 (presumably SBK2 pad). I've installed CWM and backed up too. No promises that this won't destroy your pad/steal your gal or boy/shoot your dog.
Step by step
1) Download
http://www.multiupload.com/X65RBVD2MB
2) Unzip so you have just have WW_epad-user-8.6.6.19.zip. Keep this zipped and copy to root of external SD.
3) Reboot with card in place, don't enter recovery.
4) When it booted back into the OS I had a triangle in the notification bar. I clicked this and it offered to install the update.
5) After tab updated as usual I just re-ran Razorclaw and I had root back.
Suggestions
It would be useful for people to report info with posts about success or not. What SBK, serial number (B70 etc) and current firmware are you on? I'm no dev but hopefully we can make things easier for others.
