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.

To pinpoint the leak clean the area well with brush and or small wire brush. Wipe dry. Put some talcum powder or foot power on a piece of paper and use a straw to blow it on the suspect area. Run the engine  and you should then be able to pin down the problem area.

Double check that part # on partzilla.com. I cant see where that o ring would go from the parts diagram. There is a gasket behind that cover.

www.partzilla.com/catalog/kawasaki/motor...rs-76-77-kz400-d3-d4