I've since added some spacers behind the rollers so the belt doesn't unroll like it has here.
There's a bunch of issues to look at.- mostly caused by a bent shaft. As this arrangement is probably going to be temporary, I don't feel very motivated to look too carefully. New pulleys and potentially a new Y axis screw might be on the cards.
Distance error: 0.5% (measured a half a thou over 100)
Backlash: tragic. 11.5~12 thou measured. Another teardown required!
