Fuel Spill Stain Won’t Come Off

Can you remove the lock ring , gas cap and rubber flap and take a picture of the area.  It doesn't look like it's assembled correctly to me.  There could be a crack in the filler neck that is hidden also.

 Sorry I forgot to take pics when I disassembled it. Does look like its missing some gasket or whatever. Anyway leak stopped. Not sure if retightening the lock ring bolts did it. Also I wet sanded the stain as I couldn’t stand seeing it anymore. Looks normal once again. Thanks

 

12/70 260 motor, MSD, Weber 40s, 3/2 headers, Twice pipes, Tokico Ilumina, Eibach, 1, 3/4 in sways, ext oil cooler