The plastic insert is the part I can never get apart .. and I don't put anything
on it. I can get replacement tubes and wood, but not that plastic piece.
Charlie, when I disassemble a cap end for one of the Jr VII kit sets, I use the Harbor Freight transfer punch set. I start with the 11/32 (.341 on my digital micrometer). If you have one of their transfer punch sets, and have the smallest of the three rows to the front with the larger transfer punches on the back of the three rows, it's in the middle row, 4th from the right. I insert the end without the transfer point (in order to avoid knocking out the finial), take off the wedding band (as mentioned in an earlier post), and while holding the capped end in my left hand use a hammer to strike the transfer punch- it normally takes about 5 or 6 hits to knock the clip end out of the tube, though there's been occasions it's taken 15 or 20. Once the clip end is out, I use the 29/64 transfer punch (it's the middle one of the 7 punches on the back row, mic'd at .451") It's just about a perfect fit for the brass tube, virtually no room to spare. It normally takes me about a dozen stikes with the hammer to get the center coupler with the plastic sleeve(s) out, though some times it can be double that. I have done this dozens of times, sometimes several times on the same pen as I'm trying to get the grain alignment dead on between upper and lower sections (I normally wait to put the clip hardware on until I've made sure the center coupler is placed correctly for grain alignment). I've also used this on multiple pens where I decided to strip off the dipped lacquer finish and replace with a CA finish, once I got more comfortable with the CA finish technique I now use.