the vss is held on with a nut that is held onto the vss with a flare, much like a nut on the end of the brake line, takes a 22mm wrench on the ones I have. the end of the vss fits over the speedo driven gear, which has a small o-ring on the end. if it was leaking, then the o-ring is suspect.
the driven gear is held in by an aluminum plug, which is held in place with a small bolt, 6mm, iirc. this aluminum plug has an o-ring on the outside diameter that keeps it from leaking. a leak there suggests a bad o-ring on the plug.
in either case, a leak indicates one of the o-rings is bad.
