Small Engines (Lawn Mowers, etc.): Craftsman Lawn Tractor wont start, craftsman lawn tractor, fly wheel

Question
I have a Craftsman Lawn Tractor model # 917.270670.  When I turn the key the starter engages and tries to turn the engine and tries until the battery dies.  The top of the engine (that turns) moves in a circlular motion when I turn it manually and then it stops or tightens.  Is that normal?  When the starter engages it doesn't have enough power to turn the engine.  I don't know if the fly wheel is too stiff or if the starter is weak?  HELP!

Thanks, Ron

Answer
Have  you tried disconnecting and cleaning the battery teriminals and cable ends whti a wire brush?  Have you load tested the battery?  

Try removing the spark plug(s) and see if the starter will turn the engine over.

Let me know what you find.
Eric