Most likely magneto.Take the cover off and other parts to get to the magneto.Unbolt the plug cord,clean the surface were it makes contact,with light wire brush,till shiny again. Same thing to the magnite area on top pully were it contacts the plug side.Once clean, rebolt plug side lightly down to were it can move slightly. Take a piece of notebook paper,fold in half,place it between the the plug connecting side and the magnet side as you spin the top pulley around to meet. Are pull it out were they meet by hand. Just get folded paper between.Tighten the bolts down on plug side and turn it to get paper out. Check spinning with hand that the two areas clear were they make contact. Reattach other parts & try it. Hope this helps
Sean M
December 2007