Fuel gauge not working?

[Vanarama]

Hi! Having issue passing the smog check vapor test.
Smog Check mechanic said there is a vapor leak coming from the fuel gauge sending unit. Mechanic covered it with silicone and said there is still a leak from the unit.

Is it possible that these units can leak from anything more than a gasket? If so I'm thinking of repairing the unit (especially since they are not being made anymore) Does anybody have any experience with these? Anyone have one for sale?

Cheers!