You don't say what year the motor is, but it doesn't sound "new". IMHO there aren't many simplier engines than a two-stroke outboard. Get a repair manual and go for it!! I have a 84 70hp Johnson. There is no way that I would ever bring it to a shop. Not worth the repair $. If I can't fix it, it is time for a new Yamaha!!! (I'm hoping it blows up soon)