I just paid $700 to get my fuel tank cleaned and fuel polished. They removed almost 6 gallons of water and contaminated fuel. Mostly caused by the lousy placement of the fuel filler next to the deck scupper and failure of a $.79 o-ring in the filler cap (I didn't even know it had one.) So I'm posting this so that other people can take a look at theirs.
Mike
I know people who replace the o-ring, just because every so often. Its an error trap for sure.