Although I don’t work on generators, as word of advice to my customers who own them- USE THEM!
Speaking to a friend who does generator work, I am told that he is constantly replacing carburetors. It is actually less expensive than cleaning them out and rebuilding them.
Why? From non-use. The fuel in the carburetor goes bad and turns to varnish.
Remedy: once every month or two start the generator, run it for five minutes, then start the air conditioner (or both if you have two) for five or ten minutes. Simple prevention can save a great deal of expense.
On toy haulers, pump the gas out of the tank periodically (into a can or your car) and replace it with new gas. It too can go bad.