Oh, If it's leaking oil out of the transfer tube, your gaskets not sealed their. Iirc the gasket goes around the tube to seal oil splash. I thought you had a coolant and oil leak , the o-ring is for coolant only. If your rear vent is clogged & you plug the cover vent it will build pressure & leak @ any weak spot. which that gouge on the outboard side of the o-ring would cause oil to leak out. You can try & epoxy it back into shape, silicone it ( let dry before trying it), silicone the tube to the case so the oil that gets between case & tube cant come out, or get a new cover Sent from my SM-A505U using Tapatalk