Had a look at both my cars tonight, and only one corner on one car had slightly more slop than the others... took that corner apart and had a close study of where it was coming from, and pinned it down to the lower bearing being a looser fit in the bottom of the left micro-castor block.
Rather than doing the CA trick, I just put a series of crossed-etches around the inside with a hobby knife, and straight away the fit of the bearing was much tighter, and the slop gone.