Oil Level Sensor

[ZoSoAir]

Does anyone know how the oil level sensor that goes into the tank is supposed to work? I'm replacing the oil tank so I took mine off. From what I see the white tube has oil in it that wont come out. The tanks was empty when I removed it and I had no low oil lights on before. Should there even be oil inside the white plunger? Is there a weep hole thats plugged somewhere?

Thanks

 

[Spider4real]

Should just be a float that moves up and down the oil sensor