ORIGINAL: Charlie P.
Fill and plug as you mentioned (Titebond & balsa) then re-drill carefully with a 3/32" drill, using a press if you have one available. The smaller drill will be less apt to follow the old hole. Then drill them out to full size
The only thing I would add is to use a brad point drill. It will offset the tendicy to follow the glue paths, some what. It is also easier to get started "on the mark"
Don