newel
One can fasten down a newel post using a screw driver. The screws can be used to fasten the newel post in place. Alternatively bolts can be used for this task.
A bannister post is called a ( Newel Post )
bob Marley
a newel post
A 'Newel'
Try http://www.distinctivewooddesigns.com/newelposts.php
If you're referring a reference in my favorite Christmas movie, try a search for "newel post".
Newel also spelt newell
The post actually is the banister. The fat bit that you slide your hand on is called a handrail or a balustrade.
A newel is part of a staircase and is the vertical post at the foot of a staircase, at angles where the staircase changes direction or around which wind the steps of a circular staircase.
If the post has actually come out or is loose and wiggles there is generally nothing possible that can be done to repair it, the entire battery will need to be replaced.