My Permagreen Magnum started to run rough the other day. It sounds like it is not firing every time. I changed the plug, cleaned the carburator bowel, and it gets gas. It is a year old but has 450 hours. I am thinking it is the coil. The dealer is picking it up today. Anybody with ideas? Luckily, I bought a backup Permagreen this spring. But I have not had time to customize the spray system, so it is not as fast.