A few years ago the Jr Gent/statesman II kits changed over to "square threads" because the caps on the kits kept coming loose all the time. The square threads did help the situation but I'm guessing that taps and dies will be hard to come by to say the least.
It's a long shot but if it were me, I would call Craft Supply and see if they have a clue as to the thread sizes.
A few years ago I sent in a section from the Jr Gent pen so the tap and die company could determine the thread size, perhaps this might work for you too.
