Small Engines (Lawn Mowers, etc.): No fire/Compression?, crank shaft, briggs stratton

Question
Briggs Stratton 5bsxs-7242vf Started and ran first time the season, ran for cpl mins no prob.  Engaged blades heard a loud noise (metallic)but didnt hit anything.  Seems to have lost compression...and fear the worst case scenario.  Plugs magneto good, fuel, but no fire.  Can turn flywheel by hand seems to have comp and then loses it. suggestions?

Answer
Wade
First of all this may sound stupid but was the oil full up to the correct line?
What you can do is get a compression tester to make sure you can hold compression. If it moves after you hit the compression stroke then you have the exhaust stroke,that's where it would spin easier.When you engaged the blades the electric clutch may have went bad causing some problems. Try to disconnect the power wire to the clutch it is on the engine crank shaft on the bottom of the engine,you will see 2 wires going to the clutch, these just unplug.Then try again  to start.

You say the magneto is good how do you know for sure,if your not getting spark it could mean your mag is bad or there is a safety switch preventing the engine to start or turn.Let me know what you found out it could be a number of things. I would need more information in detail.