While trying to jam up the engine to keep the crankshaft from moving, I put some string through the spark plug hole. However, it somewhat disintegrated and left some string inside the engine. I ran it for 5 seconds (started up easier than it ever has before- maybe because the clutch was off and no longer holding it back?) hoping it would come out the exhaust but I don't think it did. Should I take the head off and check to see if it's still there, or should I just burn it out?