which carb did you find sediment in ? as it was clean when it left i checked ! so if it was in that one it came from somewhere so maybe that will be the last of it i hope you have a spare condensor ? all the good ones i have are on running machines . it should be a constant spark yes but they always seem to run a little rough . while you at it changing the condensor check the top seal too . remove the cam and some fuel on the seal looks for bubbles