Wahoo Kickr original model, noise (again)

ibgarrow

My version 1 Kickr makes a scraping noise, because the flywheel has no clearance between it and the shroud behind. It also rocks slightly if I move it by hand. I’ve checked the Woodruff key isn’t damaged. If I tighten the flywheel securing nut, the play disappears, but the flywheel binds stiffly.
Am I missing a washer or spacer behind the flywheel? I can’t feel any play in the bearings.