Nick, from the sound of Dave's report above, he moved the cross shaft in the worn out hole to where it engaged with worm gear shaft and held it in place with some sort of clamp. You should be able to see the two gears interface to find that correct position and then use something to keep it in place to try and duplicate his repairs. On that thought, I have no idea how he applied the JB Weld. Without something to act as a barrier between the rotating shaft and the material, no idea how the repair worked without the JB Weld hardening in contact with the shaft. It seems some kind of thin barrier between the shaft and housing is necessary to prevent that from happening.
Perhaps some of our other Art Deco truck owners may have more info on that topic???