Small Engines (Lawn Mowers, etc.): Fly wheel magnets, valve clearance, engine specs

Question
Hello, I have a 11.5 Tecumseh ov ride on lawn mower, and the magnets on the flywheel had smashed except for one.I have two questions, firstly how many magnets should there be on the flywheel, secondly, when i turn the engine over without the plug in,the engine rotates ok, but when i replace the plug, it turns a couple of times but stops rotating,turn the key again and the same happens. I have checked that the valves are free but now i am stuck what to do. Thank you for any help that you can give me. Jerry. ps The model number is OV358ea.

Answer
Which magnets smashed, the inside/internal or external flywheel magnets?  I will see if I can find some info but I can't recall ever seeing any info on Tecumseh flyweel magnets.

Have you checked the flywheel key and valve clearance?

The service manual for OV engine is Tecumseh 740043.  The link below is very similar but covers the other OHV models.

http://www.smallenginesuppliers.com/html/engine-specs/tecumseh/Tecumseh_4-Cycle_

What does the engine power?

Eric