I Have a Sears mower about a 1993. A 12.5 B/S engine single cylinder. I had mice build a nest and chew the spark plug wire a few years ago. I taped it and it ran good. Then engine started taking 20 tries to start. Replaced the magneto. Still takes 20 tries to start.Instant start is no help. The oldest son mowed an acre it stopped. Now No Start. My question is,you need + power to the magneto with the key on correct? Have no + to the lead.Does the mower neck have a switch? I have bypassed the dead man switch on the seat,it was bad. The wire from the ignition switch to the magneto does have continuity so it's intact. I replaced the ignition switch today also.