ORIGINAL: Mark S
Bowfishing Extreme carries the shafts. Just pull the wires off the switch in the head remembering where they go. Take the screw out holding the head on. I heat the base of the motor a little where the shaft threads in. Grab the shaft with something and thread it out trying not to let stuff fall into the motor. Might want to keep the thing upside down. The shaft is stuck in there pretty good, but it will come out. You'll have to extend the wires for the extra lenth of shaft. Thread the new shaft in with the red Loctite. Attach the head in the opposite direction it came off. Hook up your wires and you're ready to shoot!
Take the armature out of the housing before you heat the shaft and the housing up. You also need to get every bit of old glue out of the housing or you will take a chance of cross threading a $40 shaft. Those threads are like 32 or 48 treads per inch. I use a little wire brush on my Dremel tool that does a nice job.
Bowfisher