I once had to replace a number of balusters in a cedar railing. The challenge was to do it without having to take apart the entire railing section to insert the tenons on the balusters into the holes in the handrail. After thinking of a variety of schemes, I came up with this simple system. I used a bandsaw to cut a narrow and slightly irregular diagonal kerf in each baluster. I applied waterproof glue to the cut surface of one of the halves and inserted the piece into the hole in the tread. After sliding the other half of the baluster up and into its hole in the handrail, I matched it up with its mate. To hold the pair in alignment, I clamped the thin ends together and drove a screw into the middle of each baluster.
When the glue dried, I removed the clamps and cleaned up the gluelines. The balusters were ready for filling, sanding, and painting.
Keith Ojala, Hancock, MI