I have got a small self propelled Cubcadet that I use just around small yards and lots. It is less than a year old and already I took it in to get fixed. They said they didn't know what was wrong with it??? They just changed the plugs and filters??? I started having loud pops out of the exhaust, and now won't start.... To me it seems it maybe the spark plug getting fowled, but I haven't really used it that much since they worked on it??? Maybe gas? Ideas???