Heres the sending unit w the "Pinot Noir wine bottle cork" from the factory in Milan. So you can see as the lever n cork swing from buoyancy it moves the metal lever on the copper toaster area which is reflected on the gas gauge. This unit failed and before i opted to buy a new one from Centerline in Colorado i thought to brush clean off all the rust , debris at the terminals n clean up the wires n connections etc..Thats all it took to bring the fuel gauge back. Of course these old style gauges fluctuate from E to F as you drive because the cork is moving in the fuel tank . A modern Benz or Nissan wont do that.