Leaning gate posts can occur if the original post is not set properly whether it be the depth, width or amount of concrete poured. Most often, if you have a sagging gate post, it will need to be completely replaced. There is a small possibility, however, that packing the hole could stabilize the existing post. Either way, you are going to need to seek professional advice to help you better assess the situation. When that time comes, please contact Family Christian Doors and speak to a specialist to schedule your free on-site assessment at 972-292-7144 for Dallas or Fort Worth at 817-224-2227.