I got two modern Sonnets, I love these very much. https://www.fountainpennetwork.com/forum/topic/348767-parker-sonnets-sterling-metro/ But the ink, after a week or 10 days, it vaporizes (or dry up) inside the cap, all. Very frustrating. There are three C shape slits at the top of the cap, and I think they are the windows that vaporize the ink. So I use a 5 ml syringe to inject some glue inside the slits. The glue I used is the cheapest transparent one. It is transparent and can be used by a syringe. And after it drys, it wont leave any stain like grease or oil. I did it weeks ago and the ink stops vaporize.