About the large metal sheave that the jib halyard turns around up top. It has a 1/4" pin thru the center of it and a cotter pin holding that in place. The 1/4" pin is the problem(too long). you need to take out the cotter pin and add a washer or 2 under the cotter pin hole of the 1/4 pin while squeezing the sides tight against the sheave with pliers as you put the cotter pin back in. Also bend the sides back flat if necessary. The jib halyard is very skinny and if there is any gap next to the sheave the halyard will find it's way in there. your halyard may be damaged from jumping off the sheave as well, and need replacement.