Hi, I have a couple of engines I received with my plane. There is a os 60 complete with muffler - looks clean and in good condition. I dont know much right now about how they operate and maintenance. I try to spin the piece where the prop goes but it wont turn at all - atleast not with my fingers. What is the best method to use to take it apart and see if it is stuck and what to do to unstick it and get it ready to run.