i think it has been tested. look back thru the thread.
best thing to do is find a "firmware.zip" file for your particular variation. this firmware file is frequently pulled from the OTA update package for folks to flash and update their firmware. this zip is not encrypted,and can be unzipped conventionally with 7-zip or other utility. all youll need to do is rezip your stock recovery image with the android info document from this file. you can be locked,but you must be s off for this to work.
EDIT : Well I'm not sure whats the problem now, I found the firmware file for my software version, did what you said and it seems to have flashed the stock recovery (when i go into recovery now it shows up red triangle with !) booted my phone up and disabled SU and downloaded the OTA update, but it gets about 3/4 of the way through and comes up with red triangle !......... feel like im fighting a loosing battle at the moment. this is the 3rd days of trying to get this sorted
EDIT : Tried again and the bar goes all the way to install.....phone has restarted and android is now upgrading.... fingers crossed