Hey Tanner,
Have you got a rust leak at the bottom of the tank!
I did so I emptied the tank and drilled and fitted a brass bung at the hole.
Also helps if you want to drain your tank.
Just drain your tank, blown air through your tank out of the inlet and use a breast drill to drill the hole.
Insert brass fitting like a nutsert (through your sender unit hole) so it expands and holds in place, use a copper washer to seal and fit a brass threaded bung.
You may get a few more years out of it!
Cheers Phil.