I had my first leaker the other day. I was doing the pump cover gasket tsb and found the high pressure fuel pump to fuel cooler line was very hard to take off. So I preformed the leak test and found fuel just pouring out that line that was hard to take off. I tried to re seal it but it would still leak even with new nuts and seals. I inspected the line and found the surface were the o-ring sits was concave. I guess they had torqued the copper washers too much at the factory and it damaged the line so that the viton would not seal. Man that 5 minute test saved my ass, and my pay check!!!!!