Please excuse my ignorance, but I'm not sure where are you referring to.. is this where the door/front windshield/roof meet? or where the door/roof meet (closest to the door handle). The word "flapper" makes me think of the plastic, spring-loaded covering near the door that covers the soft top storage area... mine are broken so water is free to flow into the roof storage compartment. I also found evidence that many convertibles have water drainage/filters inside the soft top storage compartment that need to be cleaned out regularly. The miata is a good example but I couldn't figure out if the capri has something similar...