Mag engine starter dog

[Amilcar John]

I'm building a mag engine from various bits and have used a Kiddie (billet) crank I bought some years ago. When fitting the timing gears, the hex on the starting dog does not abut and locate the crankshaft gear as I would expect it to, but stops short, as the thread on the dog does not extend all the way to the hex. I don't have a good assembly diagram and the exploded parts list I have shows only a lock washer in addition to the dog. How should this gear be located? Is my crank designed for the later coil starter dog?