To make sure I'm following, the jug is the cylinder, the sandwich is where the metal part of the crankcase meets the two plastic sides? I don't have specialty tools or even a compression tester. Was hoping to not tear down past the top end, but I get what your saying about air getting in. Might just throw a cheap Chinese top end and carb kit in it, increase my oil to fuel ratio, and see what happens. Best case scenario it runs. Worst case I paid $75 to learn a lot and am back in the same spot.
I worked that oem cylinder with some 150 and the plating is scored clean through. After reading a sampling the oil threads I'm convinced I should to go from 50:1 to 32:1, especially in this older saw. Wonder if that is what fried it.The last couple times Grandpa ran that saw was with my gas.