I'm in the middle of a tire change and decided to pop the rear gear case off the swing-arm to grease the input shaft splines. I noticed when I pulled it off that there was a O ring floating on the shaft between the back of the gear case and the splined part of the saft. There looks like a pretty big U shaped grove just behind the splined part - is that where the O ring is supposed to go? Is is supposed to seal the grease into the 'socket' that the splined part of the rear case fits into? I believe the O ring is 92055c on the fiche:
(https://www.vulcandrifterriders.com/forum/proxy.php?request=http%3A%2F%2Fcdn.partzilla.com%2Fdiagram%2Fkawasaki%2FC19%2FC1990%2FE3132.png&hash=fca4236419bf709d98289a32cb9ce67ec28cc852)
I'd replace it if I were you. That's where it goes, but if it got out of its groove, then it's damaged