Small Engines (Lawn Mowers, etc.): Hard Start, compression stroke, battery cables

Question
I have a Craftsman 12HP OHV rider # 917.254620 and Tecumseh # 143.386012. Rebuilt carb, new plug, checked valve gap .004 and a new battery today. It will turn appx 1/2 a revolution and hang. If I manually turn it past the compression stroke and try it again it starts and runs fine. This occurs at each starting. I do get an occasional backfire at the hanging point. I read the answer with the possibility of a galled piston and friction in the cylinder. This one runs super once started and mows for hours at a time.

Answer
Have you checked the flywheel key?  Although these engines rarely shear flywheel keys I would check it just in case.  Is the battery in good shape?  I would also dis-connect the battery cables and clean the terminals and cable ends with a wirebrush to ensure you have a clean connection.
Let me know what you find.
Eric