I've run into the same problem. However, I found the following solution resolves the problem every time.
- pen has been assembled, but the twist mechanism is stiff, or even non-functional.
- take upper barrel to your drill press (with finial and clip removed).
- I use a transfer punch size on my drill press that will fit through the barrel.
- place the barrel with the center band end down on top of your pen vise. What you want to do is press the transmission and clip bushing through the barrel. Make sure that the transmission and clip bushing can pass through the opening in the vise freely. Be VERY, VERY careful that the edge of the transmission doesn't catch on top of the vise as it is being pressed through, or else you'll ruin it.
- After pressing the transmission/clip bushing through the barrel, just place it back in the barrel and you'll find that it will work perfectly now - if everthing else is right.
- a safer procedure is probably just press the clip bushing through the upper barrel after you press the central band on.
- NOTE: I don't try to hold the barrel in the vise itself for fear of damaging the barrel. Place the central band end on top of the vise with space for the transmission/bushing to go through.
- One other thing that can cause a stiff twist is if the lower barrel is a little bit too wide.
The FT American can be a fussy kit to use, but I really like it because there is no cap to bother with.