There is so much “stuff” in gasoline today that is not native to the crude oil from which it was distilled. There’s all kinds of additives to improve this, or stop that, prevent the other that over time they begin to settle out. It’s not a perfect mixture today’s gasoline, it’s more an emulsion of heptane,octane and nonane mixed with some less soluble and some more soluble things. And it’s those things that can get stuck in the carburetor’s microscopic fuel passages when you let it sit over the winter. Help yourself, and drain out all the fuel you can.