A loose chair is the most common — and most fixable — problem in any secondhand haul. You need less than you think.
Most wobble is old glue letting go, not cracked wood. Work the joint apart gently, clean the old adhesive back to bare timber, and it will take a fresh bond as if new.
There's a line between honest wear and neglect. Restore function; leave the story. A century of hand-polish on an armrest is worth more than any refinish.
New to it? Start with the beginner's kit.