First post and need help with saw. Purchased saw not running, previous owner said while cutting saw just quit running and would not restart. He installed new coil, carb and spark plug. I got saw, checked spark, not good, adjusted coil and installed correct ngk bpmr7a plug, have consistant spark. Checked compression, 6 pulls about 160. put either in no fire, not even and attempt to fire. Removed muffler saw minor scoring and burn marks past ring, put penitrating oil in upper cylinder and rolled piston up, saw bubbles blowing out around piston. Also has a sound like air whistling by. Is this a sign that it needs new piston and cylinder. Thanks for any help.