Ok, so I finally got the flywheel off and the key was sheared and one of the coils was cracked really bad and one of the cracks had a small amount of melted metal coming out. The ignition system is a Magneto the coil's model number is F12057. I have found a replacement key but the OEM coils are used $120. Would a new Sierra 5181 Coil work just as well? Its much cheaper. Also do I have to set timing once i get new key? And is there anything else I should replace?