Tecumseh 6.5 hp keeps on breaking the timing flywheel Pin and make a loud banging

Never experienced this before If the spark plug is out and when pulling the pull cord the engine is nice and quite turns over perfect. When placing the spark plug in (correct plug) it makes a noise like the blade is hitting the side of the mower (blade and shaft are perfect) It seems when under compression the engine makes noise. I replaced the timing key and the lawnmower starts for a minute or less making that noise and the engine stops and the timing key is broken again. I removed the bottom end of the engine and everything looks perfect the only thing I can feel is that the piston piston rod moves a bit from side to side on the crank-shaft but will not move up and down at the piston rod. Any suggestions

Remove the blower housing and with the flywheel magnets facing away from the ignition module try to wiggle the flywheel in different directions. I am wondering if the top bearing is damaged and the flywheel is hitting the ignition module or something else.

ILENGINE said:

Remove the blower housing and with the flywheel magnets facing away from the ignition module try to wiggle the flywheel in different directions. I am wondering if the top bearing is damaged and the flywheel is hitting the ignition module or something else.

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I have the bottom of the engine removed I guess I will have to put it together to test. Is there a bearing on the top or just the housing with an oil seal. I also thing I tried what you suggested and did not experience any side to side movement just an up and down movement.