Yeah, as gstallons said, the seal has likely swollen or as Scud is about to say, someone smeared some adhesive/ gasket sealer on it. once the fasteners are out, you can try carefully turning the sensor while continuing to lift it out a little at a time. Mine was also leaking through the wire lead, which I ended up using JBWeld to seal up. It's continued to work for a long time now. My oil sender has never leaked, but don't let it hear me say that . . .