Yesterday I have disassembled a rOtring 600/2.0 and a 300/2.0 to compare their mechanisms, and after reassembling I found this small rubber ring.
I didn’t notice anything falling out of the pencils, and both work perfectly. However, since there were no other items near them I assume the ring belongs to one of the pencils.
Does anyone have an idea?
ahah, Gunther — I have 3 or 4 of those, including one that I’m keeping in my wallet for nearly a year now… but I have absolutely no idea how it got there or what it’s for! Pretty sure it’s there for a reason but I can’t remember what it was.
Wish I could help!
(usually it’s fountain pen stuff, but idk…)
hey, I just tried to disassemble both those pencils… your ring is probably from the plastic lead chamber of the 600, I was unable to pull the tube out because I think there’s ring around it. You can push it back in place with the push button…
i think.
Thank you – that worked! I don’t notice any difference but I don’t think the manufacturer put the ring there for no reason. Perhaps the ring was placed halfway up the plastic tube to prevent it from deflecting radially when pressed (the 300 has a metal tube where this risk does not exist). However, you can no longer get it into this position without a suitable tool.
Maybe with a straw (for drinks) you can push it near to the step inside.
But in my mind that piece is a silencer, even if it’s not its primary function, it prevents the plastic tube touching the shaft and making those irritating noises… 
I tried to attach the ring somewhere on the plastic pipe, but found that it prevented the pipe from moving freely. It’s now at the step right below the clutch where it doesn’t interfere with the function
