Yes, the tailwheel assembly. Sand the bottom of the fuselage flat, down to the fiberglass (or kevlar) and glue a piece of approx 1/2 x 1 1/2 inch piece of carbon fiber sheet (the kind that is about 1/32 inch thick). Glue this to the bottom of the fuselage then sand around it to blend it in. Already finished and painted? No problem, you can still do this and its not noticeable, since the tailwheel bracket hides the carbon fiber sheet. When you use wood screws to hold in the tailwheel assembly on, the carbon fiber will provide extra strength for the threads to hold.