My 140 died on me after 30 minutes of mowing. I've read threads on here before about the coil being bad, so I threw a new one on and still no spark. It will crank and has plenty of gas, but no spark. This happened last week and I trouble shot for about two hours checking voltage to the points and so on, everything checked out. Suddenly after about two hours it started and ran fine. What do I check now? BTW it also has a Kirk pointsaver. Has anyone ever had a failure on this? I restored this tractor about 4 years ago and everything has been great up until now.