Tonight I was showing a customer a Jr. George as an example of a nice pen kit, but to my chagrin the cap would not screw onto either end of the pen. Upon further inspection it looks like maybe there is a piece inside the cap that holds the threads. I'm thinking that piece has somehow been pressed too far into the cap so the interior and exterior threads don't engage when you try to twist them together. Is that how these work? Have you heard of that happening before? Any idea what could have caused it?