Same thing happened to me. Flashed 1.4 and lost root... Fixing permissions did not help. Is Odin my only way to get root back?
Sent from my SCH-I510 using XDA App
did you try this? use Cwm and flash the superuser zip package.(superuser package can be download from link below)
EDIT: make sure you mount /system before flashing. Also did you Odin the latest cwm and use this to fix permission?? http://www.toms-world.org/android/page/rootinstructions
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