@neildarlow@mastodon.org.uk Unfortunately my issue is different - I'd already tried that (albeit with two drink cans), but running the levelling procedure just re-skewed the axis again. I think it's an issue with the actual probe itself.

(The reason the axis skewed in ModBot's case was probably a design flaw in the printer itself - the ribbon cable for the extruder gets in the way of the frame and so only one side of the Z axis actually reaches its end stop, the other side is held back by the cable)