OK so the axles have been glued, and now I've been fettling the bearings into their slots. Very simple, a couple of strokes in each slot, and remove the burr with a scraper.
Check the bearings fit, then fettle the bearings, using a 1/8" reamer.
And this file, which is an ordinary file, but I've run the edge against a bench grinder to take off the teeth. It can only cut on its sides, so I can enlarge slightly the groove in the bearing to enable it to rock so the axles can move around.
I've also been working on the wheels, these are Ultrascale, I've filed a slot in the back of the tyre ready for a Bill Bedford/EMGS society shorting strip.