1968 Dart fuel sender replacement
The hole is the tip of the are being worn off.
There is a how to article explaining a way to repair it.
I would not do all of the items in the artical. But repairing the tip I would do.
If you do that repair, go on Amazon and buy some electrical flux and solder. With a bit of protection of the wire board via a bit of thin card board and some aluminum from a soda can you could put it between the board and the sweep to do the soldering.
OEM Fuel Sender Repair 1967 Dart