76 KZ400 left side oil leak

Always seemed to have seepage for the couple years and few hundred miles I've owned the bike but seems to be getting worse so I'd like to fix it but seeing posts on FB groups about replacing and o-ring (#92055-098) but want to make sure that's the fix before ordering anything. Photos attached of both sides but looks like it's primarily leaking on the left side near the big cover.  Thanks in advance.