Dave,
When I removed the cowl I found that the teflon tube between the NMG muffler and the header was kinked and had become partially blocked. The header came loose the day before the engine quit and I tightened too much and twisted the teflon tube very slightly. It became kinked and then split thru the side. Some of the exaust was still going thru the muffler as the sound was not changed. I still cleaned out the regulator. It will take a few days to get a new tube and try the engine. Should I get a silcone tube instead of the teflon connector that came with the NMG muffler from Central Hobbies? Thanks.