The short answer

Start at the ground line and work upward. A loose picket or rail can be repaired without replacing the post, but a post that moves independently, feels soft, splits around fasteners, or cannot hold a gate load is a different problem. Cosmetic filler and a new coat of stain cannot restore missing wood fibers.

Sort the defect

Symptom Likely scope What to verify
One loose board Picket or fastener repair Is the rail and post still rigid?
Sagging rail Rail, fastener, or post movement Does the post move when the rail is steady?
Gate drops Hinge, latch, post, or footing Which component carries the movement?
Softness at soil line Post decay Probe only if safe and do not confuse surface hardness with capacity.
Water held against post Drainage and detail problem Is the repair addressing the wetting source?

Photograph the post from several sides, note gate width and slope, and mark the extent of soft or split material. Do not dig around a post without checking for utilities and property boundaries. If a fence retains soil, supports a privacy screen in high wind, or borders a pool, the consequence of failure is higher.

Compare estimates honestly

Separate board removal, post extraction, footing work, new post, rail and panel reset, gate alignment, disposal, and finish work. “Brace the post” and “replace the post” are not equivalent treatments, even if both make the fence look straight for a short time.

Limits

This guide does not determine property-line responsibility or structural adequacy. A gate that can fall, a pool barrier, or a post near utilities deserves qualified help.