I have a Rotring 600. I haven't used it in several years. Made a stop on the way home from work today and got some new cartridges. Popped one in and got it writing. I replaced the cap (definitely closed, as it's easy to tell if a 600 is actually closed or not) and walked away for a few hours. I came back to my desk and started to write again, but the nib was already dry and wouldn't start up. I'm sure I can run a little water over it and get it flowing again. However, I'm recalling that the reason I put it up a year ago is because of the same issue. It's the original Rotring nib that came on the pen. Any thoughts or solutions?