I have always felt these carbs (used on many different manufactures) to be sensitive to sticky float valves. When I was young the oldtimers ALWAYS shut the fuel off when not in use. I found a new style valve (made by a family business in MA) Grose or gorss jets work best .It is basically 2 small balls on top of each other instead of a needle,the float hits the first ball,which lifts the top ball into the seat. Because the balls rotate a little they seem to self clean,plus they keep very precise level in the bowl.
I also go to e-bay ( I am lazy LOL) and buy a 12volt electric shut off valve (mine have all been converted to 12 V) and put it in line - now when I shut the engine off the fuel automatically shuts off too.