Fix I9300 "e: failed to mount /efs"

Samsung i9300 S3 16GB Hangs on Samsung boot logo screen.

At the moment flashing is possible via Download Mode.

Can access the recovery mode , the invalid /efs is displayed on the recovery screen.

Tried Stock and Custom Roms, single and four file options, pit repartition, still hangs at the Samsung logo screen.

Need to rebuild /efs. No efs backup available.

ADB through recovery screen adb update possible.

Team-viewer can be setup. ADB available on this win7.
GMT 11am to 7pm.

I've tried every option available except rebuild the /efs.

Need an expert hand to get this sorted. Thanks