Back in the 80s–or maybe the 90s–I destroyed a couple of Rotring 400 fountain pen sections by first using technical pen ink in the pens and then trying to unclog them by soaking them in technical pen cleaner. This was a really bad mistake, because corrosive substance + anodised aluminum = disaster. Fortunately, Rotring GmbH saved me from myself and replaced the sections free of charge (they weren’t under any obligation to do so), including the nibs. The damaged section sleeves had to go but the nibs had repair potential, I thought; but after much effort they remained irreparable and I put them away for close to two decades.
In 2010 I tried unsuccessfully to get the nibs working again, and although I resolved to finally get rid of them — this time, really, honest — my pack-rat tendencies got the better of me. Back into the parts box they went, neatly labelled as FAULTY–THROW AWAY!