Cleaning Gummed Up Generator

I have a gummed up generator/carburator. I would like to learn how to clean it and not have to pay the service fee at the dealers. Does anyone know of a good resource for learning how to do this? It's the typical Onan 4000 model.

Also, I need to replace the motor on my fuel pump station. Is this hard to do? Resources available for learning how to do this?

Thanks!