A loose banister is a shaky situation that can lead to accidents and even injury. You can easily reattach most newel posts. There are two basic types: a solid turned newel made from a solid piece of wood turned on a lathe, and a box newel made from hardwood lumber with a hollow base. They attach differently to the floor or step. The method of attachment is the key to repairing a loose newel post.
Pry the base trim away from the bottom of the post with a pry bar on all four sides. Pull the nails through the trim's back with locking pliers to preserve the face. Set the trim aside for reuse and locate the mounting brackets, at least one on each side of the newel post.
Tighten the screws in each bracket. Screws run into the floor and into the side of the post. Take note of screws that do not tighten properly and remove them, turning them counterclockwise. Fit slightly thicker, slightly longer screws into the holes in the bracket that the stripped screws came out of. Tighten snugly with the screwdriver.
Realign the trim around the base of the post and nail it in place with a pin nail gun and 11/2-inch nails. Use at least three nails in each piece.
Remove the trim from the base of the newel post as described in the previous section. Locate the mounting screws through the faces of the post into the mounting block inside the post.
Loosen and remove the screws from the post, turning them counterclockwise. Remove the screws holding the rail to the post at the top and lift the newel post off the block.
Locate the mounting screws in the wood block underneath and tighten them to snug the block in place. Replace any stripped screws with slightly thicker and longer screws. Tighten them with a cordless drill. Fit the post back over the block and reinstall the mounting screws through the sides of the post. Replace any stripped screws with thicker screws and tighten them with a drill.
Refit the trim and nail it in place as outlined in the previous section.