Got this garage find and engine was free when parked a year ago. YOU KNOW THIS FOR A FACT OR DID SOMEONE TELL YOU THAT? Craftsman DVT4000 lawn tractor. Was seized when I got it. Small amount of Mystery Oil in cylinder over night freed it. Now it turns very hard (breaker bar on shaft bolt). Starter will not rotate it. Plug is out and belts are off. Where should I go next? Thanks