I use a cone shaped deburring tool in reverse to open the hole enough to fit the knuckle. Once you find the right one you will be good to go for a life time. Wet the hole with a Q-tip and use pacer hinge glue or something similar. I like it better then epoxy, plus epoxy does not stick to the plastic . Take some tool oil or melted Vaseline and put a drop on the hinge point and it will not be effected by the glue. Also take a drop of oil on your finger and rub the covering on either side of the hole. If you do find the pin sticking a drop of acetone will free it up easy enough. Don't be afraid to use an extra pin or two in each surface. They move so freely your servo will never notice them.