"retractable ferring" ?? I'll guess you are speaking of the wing. Under the wing you will see a plate that the wing attaches to. Most leaks originate from a poor seal of that plate to the cars body. Instructions as to getting that plate off varies a little in respect to a coupe or a convertible. You remove the trim from the inside of the car below the wing. When the trim is off you will see the studs/nuts which must be removed to lift the wing up and off the car ( you will also disconnect the electrical connectors). I used a putty like sealant that comes as a rope (Mortite, Weatherstrip and Caulking Cord) to make a new seal. There is also a possibility that the gasket around the gasoline fill door is leaking, or the electrical protective cover near the hinges of the trunk/hatch is allowing water to enter the hatch, but most of the leaks are the poor seal at the wing attachment plate. There are threads on the forum that have pictures and more info as to the repair.