Early on there were a few V-Mods that had pin holes in the lines around the area of those tiny clamps, like the worker nicked them or pinched them when putting the clamps on. You can test a little by gently pinching a line shut with needle nose plyers and pumping the bulb. The bulb forces gas into the tank after pulling it through the carb. If you pinch the pressurized return line and get gas at the fitting then you know. Pinch it between the fitting and the tank. For the suction line pinch it off between the fitting and carb. The return line pressurizes the tank which then gets forced up the fuel line and towards the carb. If there is a leak it will show itself. Obviously you need to have fuel in the tank and the cap tight. For a fix you can maybe just lower the clamp a little so the hole is outside the pressure zone. Worst case you can cut just a bit off the line and push it back on the fitting farther.