My carbon fibre mizzen has a black plastic bullnose attached by stainless steel screws, just below the sail, to which the foot is attached. Last weekend after a windy sail one of the screws pulled out completely and the other was loosened. When I took the screws out I realised that the mast is quite thin - about two mm and therefore not much to attach screws to. I also wondered whether there had been some electrolytic action. I took advice and have now repaired it by drilling the holes out to about 7 mm then injecting epoxy mixed with fine glass fibres until the consistency was about like mayonnaise. I turned the mast horizontal with the holes facing down. Then, using a large catheter tipped syringe, I injected the epoxy though the holes - about 7 ml through each hole and placed packing tape over the holes. The idea was to form an epoxy plug behind the holes for reinforcement. Twelve hours later the epoxy was absolutely solid. I then drilled a small pilot hole followed by a hole appropriate for the screws. The bullnose was attached very firmly.