I recommend that you check the 'new' Weber first, to be certain that it hasn't also rusted in the 26 years since it's been sitting under your garage roof....
Is the oldster's wobbly front leg just loose in the socket, or is the socket itself rusting away where it attaches to the kettle? If the later, it will need rather a lot of repair work, which doesn't really seem worth the effort, given that you probably have a serviceable 'new' barbi' ready for use.