Look at it! Behold the butyl overmold on the comically oversized cap! See the screen printed lines like a 90s basketball sneaker! Feel the forced ergonomics of the weird section! Examine the submarine portholes of an ink view window!
…It actually writes okay though. Rotring made good nibs.
Don’t use lacquer thinner. That will attack any plastic or rubber parts in the pen.
However, various alcohols can eventually dissolve shellac, including denatured (methyl) and Everclear (ethanol).
After soaking it in very hot water last night I got the bright idea to try to scrape it with a little wooden coffee stirrer. I broke the rubber gasket that goes around the post on the receiving end. So I think that tip is done. I bought a replacement tip last night for $10.