A broken fence post is a common cause for a leaning wooden fence; unfortunately, fence posts frequently rot due to their constant exposure to damp soil and wood-eating insects. However, if your leaning fence is due to a broken fence post, you can repair the damage yourself and get your fence standing tall again. Below is more info on how to do it:

How to fix a leaning fence with a broken post - tools and materials needed

• Fence post reinforcement stakes – these are commercially-available flat steel stakes that are designed to reinforce broken fence posts. They typically have a pointed end for driving into the soil and concrete and also are equipped with several holes for inserting screws or nails.
• 50 feet of one-quarter-inch polyethylene rope
• 2-foot one-by-one board
• 1-inch head screw eye bolt
• Electric drill with appropriately-sized bit
• Rubber mallet
• Small sledge hammer
• Claw hammer
• Screwdriver
• Size #9 – 2.5 inch roofing screws with built-in washers
• 50 pound bags of premixed concrete
• Garden hose
• Shovel
• Box level

How to fix a leaning fence with a broken post – step-by-step procedure

1. Remove the picket board on the back of the fence post – the picket board may be nailed or screwed to the crosspiece and post. Remove the fasteners and board, and set them aside for reinstallation.

2. Remove the soil adjacent to the broken fence post – with your shovel, remove all the soil around the fence post down to the top of the concrete abutment.

3. Attach screw eye bolt to the fence post – about 3 inches from the top of the fence post on the side opposite of the direction of the lean, drill a small pilot hole using a bit 1/8-inch smaller than the diameter of the screw eye bolt shaft. Insert the screw eye bolt into the pilot hole, and tighten it until it the eye is flush with the surface of the fence post. Insert a screwdriver through the eye if you need leverage to tighten the bolt.

4. Level the fence – tie a secure overhand knot to fasten the rope to the screw eye bolt, and pull the fence in the direction opposite of its lean until it is vertical. Ask a helper to hold the level vertically on the fence post and to verify with you when it reaches a true 90 degree orientation to the ground. At that point, ask the helper to push against the fence post to maintain the proper vertical alignment. At the same time, securely tie the rope to a nearby tree or other suitable fixed, heavy object.

If you don't have anything appropriate to use as a tie-off point, drive a 2-foot one-by-one board into the ground about 18 inches deep with a sledge hammer. Angle the board slightly away from the fence while driving; after finishing, tie the rope off to the board. Verify with your helper that the fence post is still vertically aligned, and make any necessary adjustments if it isn't.

5. Drive the fence reinforcement stakes – with the sledge hammer, drive one reinforcement stake into the ground as close as possible to the inside surface of the broken post. Your goal is to drive the stake through the gap between the concrete and wooden post so the two are as close to each other as possible. Keep driving the stake until about one foot remains above ground level. Repeat the process with the opposite side of the fence post so that both sides of the post are reinforced.

6. Fasten the reinforcement stakes to the fence post – insert #9 roofing screws through the holes in the reinforcement stakes and drive them into the fence post so they are secured. Use every hole available for your use; you will need maximum support to keep the post in its correct position.

7. Add concrete for strength and support of the repaired fence post – pour a 50-pound bag of dry premixed concrete into the hole surrounding the fence post with attached reinforcement stakes. Add water according to the manufacturer's directions, and stir the mix with a shovel until it reaches the proper consistency. Allow the concrete to cure for at least 24 hours before proceeding.

8. Finish up the job – once the concrete has cured for at least 24 hours, untie the rope from the fence and its base of support Remove the eye bolt, replace the picket you removed in step 1 and add soil to the area above the freshly-poured concrete until it is flush with ground level.