Somehow that doesn't shock me. Some Neanderthal just forcing something cause it is too tight.I couldn't get a very good picture but the goop inside the line is the lining thats in side the fuel line . It looks like it has a inner plastic lining in the fuel line. When I cut the plugged up part off and pushed the fitting back in the line the inner liner just bunched up inside the line and plugged it up again. It looks to me like the marina put 5/16 line on 3/8 fittings