The most common source of leaks is in the rubber seals but it is also possible that you have a torn roof canvas.
Mercedes clk convertible leaking roof.
Convertible roof is stuck open shut.
It drips down on both passenger and driver side near where the window meets the closed top so drops fall on the seats near the windows not in the middle of.
If waterproofing the fabric part of the roof solves it temporarily then it seems like you probably have tear in the canvas.
If you find out that the convertible top reservoir is low in fluid that means that you have a leak most likely at one of the convertible lift cylinders.
Common mercedes clk soft top roof problems.
My 2006 clk 500 roof leaks when it rains.
Roof requires recalibration or roof reset.
My 2006 clk 500 roof leaks when it rains.
Cabriolet not operating fully through cycle or stops halfway.
Hydraulic leaks or hydraulic pump failure.