I have used a red SJ double jewel pen for the last 10 years, which is very precious to me. Recently, the cap wont stay on. There is only 1mm or so where the thread catches on, then it "clicks" through and comes off again. I am not describing this well, but hope it is understandable. I noticed that there is a very fine crack in the cap, vertically from the edge of the cap to just under the cap ring. In addition, the threads on the pen itself are somewhat worn down. It seems to me that this crack, as well as the thread wear are both are contributing to the problem. The pen is in great shape otherwise, but is unusable if the cap wont stay on in my pocket (already stained one shirt).
Does anyone know a DIY repair I could do? I superglued the crack from the inside, but it re-cracked after 1 week. Any advice would be greatly appreciated. I love my pen, and dont want to buy a replacement, although I will if I cant fix this.
You need a solvent-based cement, like Ambroid Pro-Weld. Use just a tiny amount applied with a toothpick, and be careful not to get it anywhere but the crack as it will soften the plastic and alter the appearance of the pen if you do. Enough of the stuff will melt the pen into a puddle of goo.
Do this outdoors, by the way, or at least with plenty of ventilation: MEK is nasty stuff.