Other Fuel System Tank Filling/charging problems of the 2006 Mercedes Benz CLK350

Fuel leakage/puddling out of top of left fuel sending unit, most notable after filling tank. Noticed at left rear tire well of car on outside only. Initially thought that the gasket on the sending unit was faulty (fuel staining noted on top of sending unit)so replaced gasket with initial improvement of problem. After several months problem appeared to recur but now clearly worsening. Fuel smell had until recently only been noticeable after parking in garage after filling tank, most recently noticeable in open parking lot after filling tank. Improves when tank less than 3/4 full. Recently removed inspection cover under left rear seat about 30 minutes after filling tank. Fuel appears to leak out from under the electric connection on top of the 2" diameter plastic disk, or at the edge of the disk, on the top of the sending unit. A 1-2 ml puddle of fuel develops within 30 minutes of filling the tank.