How to Fix a Loose Stair Rail Post
- 1). Position the drill at a 45-degree angle at the corner of the tread and the baluster on a side that faces another baluster. Drill 2 inches into the wood, going through both the baluster and tread. Repeat this on the opposite side of the baluster.
- 2). Wipe away the sawdust from around the hole with a cloth. Squeeze white polyvinyl glue into the holes until they overflow. The glue will stabilize the post.
- 3). Wipe away excess glue with the sponge. Allow glue to dry overnight before using the railing. Movement could offset the glue and ruin your work.
Source...