Lawnmower "kicks back" when trying to start.?

I've got this one For Sure!There is a key/pin holding the flywheel in correct timing,to the shaft.What has happened is while the blade was loose,it was slamming the key hard,and as it is supposed to gets chopped or slit.Just get the flywheel key and pop the flywheel off.Remove the nut holding the flywheel on!The flywheel may need a bar with leverage,to jerk it loose from the shaft.The pin will be widened.Just line it back up and insert the new pin.When it bends or brakes,it causes the engine timing to be off stopping the engine until repaired.But to much choppings around the blade should be ruled out first.But this is right.Trust me!Thank you and Good Luck.