Take the wrap handle off and check for cracks in the bottom of the case. Especially in colder climates this is a problem. I've epoxied a few will reliable results.
Looking at my service manual, two o-rings on the oil adjustment bolt, and one on the nipple that goes into the elbow connector at the top of the pump. The grommet/bead on the suction hose is another potential leak source.
I'd send a pic but my scanner is down again...(???)