I think you can work a broom handle or something similar inside the leg to make it fit tighter, if that doesnt work I think people use that metal duct tape. Might keep your eyes peeled for a donor kettle with and ash pan.
There are some really good restoration threads here. If it were me I wouldn't put too much time and effort into it. Your gonna have nicer kettles in no time if you keep hanging out here lol
Do all of your vents move freely?