Does your neighbor mow down a hill? Where does he store the mower? A neighbor of mine kept his lawnmower in his basement. The lawnmower would be tilted at about a 45 degree angle, front end down, when carrying it up and down the stairs. Gasoline would leak out the carb and soak the air filter. I installed an inline fuel shutoff and when he was done mowing, he would close shutoff and run the engine until it stalled. No more wet filter.