My nut doesn't come off either but being my first GS, I figured that was normal.
I've had the tank of twice recently and didn't have any issues getting it back on.
sorry about your troubles... maybe something is slightly out of alignment?
2007 BMW GS Adventure
/ 2000 Ducati 900ss
/ 2010 Harley Ultra Limited
/ 1975 BMW R90/6
/ 2006 DRZ400S
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