I have a 1998 4.3l w/an aplha1 and the stern drive leaking lube out the vent hole. I have replaced the gasket and the plug. The seat appears clean, and I have scraped it down lightly with a small flathead screw driver. The plug tightens up well. The boat is winterized, covered, and sitting outside in the not too bad but still cold NC winter. Any suggestions would be appreciated. Thanks in advance!