did not know the a/v part. would have figured it out eventually. how much are you picking up used engines for on ebay? I figured that would be pretty cost prohibitive considering the low value of the saw in general.The crankshaft passes through the oil pump that is bolted to the case behind the clutch. You will need to remove the clutch.
Pull the spark plug and shine a light inside to look at the cylinder wall above the exhaust port. If it is damaged (likely) you're better off getting a used engine off eBay. I cut most of my wood with these saws, but this one has no A/V suspension so it's of limited use and not much value. They will buzz your hands numb in a tank.