remove the recoil starter and shroud, this will expose the flywheel which should have a little plastic cover near the centre, prize this plastic cover off with a screwdriver, now if you turn the flywheel (whatch ya fingers) you will see the contact points which open and close. now the repair begins, cut a small peice of very fine sand paper about 1cm by 8cm (the black one is best i think they call it hydracarbide or somthing like that) fold it in half then gently rub it inbetween the points for a little while (your just renewing the surface, your not trying to sand it down) now blow out with compressed air, then repeat, now finish with a final blow of compressed air. now remove the plug if you havnt already, and put it against some fresh metal on the engine, now turn the flywheel by throwing it round with your hand (again whatch fingers) now you should have spark, if this didnt work let us know.
Andy lee
June 2009