The only enigmatic phrase I see is "the rattle of his chain", the rest seems quite clear to me.

Hates his job, as Tinker thinks? "You have nothing to lose but your chains"? I am not convinced. More probably it's the chains of his family life, and of his unsociable mental constitution.

Or does it just mean the rattle of the escalator chains, which used to be quite a noise? Has "his" slipped in for "the", accidentally or Freudian? The clicking turnstiles certainly are physical objects typical of Underground (subway) stations.

It is not Kristofferson's task to tell us what exactly happens after the last ride and the drinking in the Golden Crown. It suffices to know that Casey's last vague hope has proved an illusion.

For those who have not found out themselves: The title evokes Casey Jones' famous last ride. A loser is contrasted to a hero.