You will need several old Cotton tee shirts,shop towels or old cotton rags that will fit in the filler hole. Drop a few of the rags in the tank take a broom handle or wooden stick and move the rags around to soak the crud. Take a coat hanger/wire and form a hook to remove the soaked rags. Repeat with more clean rags as needed. Be careful take your time,watch what you are doing so you don't damage your float assembly.