My Jet did the same thing. New gasket fixed it. Should have sent it back for a factory Warranty claim, they should have used a gasket that lasted more then 63 years!
Geoff

To clarify, this is not where the fuel gauge sender goes into the tank, it's where the fuel line goes in. There's a bracket attached to the tank held in by 2 screws that holds the line going into the tank and a fitting on the end of the line where the rest of the line attaches. I'm not sure how the line is sealed so that gas doesn't leak around it but I'm imagining it would be welded and perhaps the weld has cracked. Or there might be some kind of an O-ring seal but that seems unlikely. In any case it's not just a plate with a gasket which would be easy. Thoughts?

thinking more about this over morning tea...Does the line perhaps have a flange on it that gets a gasket where its attaches? If you undo the 2 screws will the line pull all the way out of the tank, or does it have some kind of screen on the end? If so, I guess you'd need to split the gasket to go around the line, or use 2 gaskets with the split on opposite sides or something...

Bob, this is a very common problem. That part you are referring to is the fuel line pick-up tube. It is mounted to the tank with 2 slotted screws . Save the screws or at least pay very close attention to those screws. From the factory, provided your tank hasn't been messed with, the pick-up tube screws both have special flat copper washers on them. These are needed to seal the screws once the tube is installed into the tank. The sending unit doesn't require them, as it has a built in anti-leak contour behind the screw flange, which is also soldered in the center of the tank. If it didn't have this, the slosh of fuel would allow the screws to leak all the time. A note, if removing the fuel sender, and a screw or 2 break off, make sure you don't drill all the way through the protective baffle. If you do, this will allow fuel to directly slosh against the screws and possible leak. Our tank sending unit and pick-up tube gasket set is designed to reduce that from happening, but is no guarantee.
If you remove the pick up tube, you will see the solder around the tube is usually cracked, allowing it to leak, ESPECIALLY if the tank is full or close to being full. We charge 35. to restore the tube, provided the tube is good enough to restore. These pick up tubes can be a problem with fuel concerns. It is not Uncommon to find a very small pinhole in the tube, allowing it to suck air instead of fuel and cause fuel delivery concerns and/or problems! So while it is out for repair, clean and inspect it very closely. We use soap and water solution to test after we have restored them to insure there is no leak between the bottom of the tube to the brass fitting soldered onto the end. Email or call us if we can help. 317-398-4163.