Someone, perhaps here, says to get like a $1 gallon of thinner at Wallyworld then as much steel bird shot as you dare. You will need to remove/ plug the petc0ck.
Then pour in 1/2 thinner and a bunch of shot, replace the lid and shake, shake til you drop. Pour out the mess then rinse w/ thinner. It will knock off the stuff that might go to the carb, do it longer like on a rotisserie and it will get shiny, new.