This Yamaha APX500 must have been jumped on (no one seems to know exactly what happened) as the neck was broken or sheared straight through around the fifth fret area. In 35 years I've repaired hundreds of broken headstocks but never a neck sheared straight through in the middle. The fingerboard was also separated along half it's length. The tricky bit was it didn't want to go back to it's original position as the short jagged bits would not match up.
The Yamaha APX500
After a trial dry run I got yellow glue into all the gaps, clamped the body end of the neck down to a work table and bent the head end back almost far enough for it to snap off. I then clamped the break area together with the help of two extra hands. This ensured everything lined up for final clamping with a straight wooden caul over the fingerboard. A paint touch up job finished the task.