A majority of the time, we remove the two baluster halves and use an alignment jig to re-attach them. In this instance, both the top and bottom of the baluster fit into holes. So we can’t fit a repaired baluster back in place. The procedure is to drill holes into the broken ends, fill the ends with wood-epoxy, put the pieces back in, and allow the epoxy to cure and form a dowel holding the two pieces together.
Needham, MA
Click on the first image for detailed explanation of the process.