Probably the o-ring but check the bellows too, make sure it's on the base of the housing. It will nest into a groove in the housing. But, if you're geting that much oil the o-ring is probably shot.
#4 is what is probably hard and out of service. I use part#290931765 they're green and for the RFI's not carbed skis. The RFI run a little hotter so I guess Seadoo changed o-rings. I've never had an issue, same size, just better material.