REMOVE THE HINGE POST
PHOTO BY WEBB CHAPPELL
Remove the gate and set it aside. Detach the fence section from the hinge post, then dig around the post until it wiggles freely. (If the post is set in concrete, dig around it, then break it into small pieces with a sledgehammer.) To pull out a post , give it bear hug and straighten your knees. Use this old post as a template to mark the locations of the hinges on the new post.
SET THE NEW HINGE POST
PHOTO BY WEBB CHAPPELL
Prop up the unsupported end of the fence section until it's level. Now, fill in or dig out the hinge-post hole until it's 3 feet deep and drop in the new post. Hold it upright in its hole and check that its top is level with the top of the latch post. To make sure that the gate will clear the ground by 2 to 5 inches, hold a level at the height of the lower hinge.
ATTACH THE FENCE SECTION
Place a level against the side of the hinge post facing the gate opening. When the level indicates that this side is vertical, attach the fence rails to the hinge post with galvanized deck screws. Remove the prop under the fence section.
Tip: A wooden wedge cut from a piece of old fence post makes a useful prop when leveling gates and fence sections.
LINE UP ALL THE POSTS
Tack a nail to the far side of the nearest fence post, about a foot above grade, and tie a mason's line to it. Pull the line around the post's corner and several feet past the latch post. Attach it to a stake so that the line touches the latch post. Move the hinge post over until it just touches the line, and make it plumb. A post is plumb when a level shows that two adjacent sides are vertical.
STRENGTHEN THE FOOTING
Brace the hinge post with two 2x4s: Screw the studs' upper ends into opposite sides of the post 3 feet above grade, and stake the lower ends in the ground about 3 feet from the post base. Mix up two bags of concrete and fill around the post. Stop filling when the concrete is 3 to 4 inches below grade, enough to hide it under topsoil. Let the mix cure overnight.
REHANG THE GATE
If the latch post rotted, as this one did, replace it following steps 1 though 4; you won't need concrete. Set the post in a 3-foot-deep hole on 2 inches of tamped gravel, check that its top is even with the hinge post's, then fill the hole with firmly compacted gravel and soil. Reattach the gate, making sure its top rail is level and that it clears the ground by 2 to 5 inches. Close the gate and attach the latch where its bolt hits the latch post.