as long as you're in there, here's how I verify spacer fit-
Set both bearings tight to the hub shoulders, with no center spacer
Measure bearing depths from hub flange, both inner and outer races
Remove one side bearing, place spacer. Re-install bearing until it bottoms
Re-measure bearings; if you have *zero* change from no spacer measures, it's too short.
If driving the second bearing home changes the depth of the first bearing, note by how much. These small bearings have very little clearance, so I would say if your center (spacer) race moved by .001" to .003" you're in good shape.
If you get more protrusion than a couple thousandths, your spacer is long- which can overload the bearings if the outer races are too tight to float in the hub, which they should be.
I would rather shim up a short spacer than try to work with a long one, as it's important to have the ends perfectly square to the centerline of the bearings, hard to achieve with a file or stone.
If your spacer is long, you *can* drive the bearings against the spacer with an appropriate driver that touches only the inner race- then when the driven bearing finds home, the direction of forces on both bearings will load the races equally and center themselves up. That does leave you with a couple or few thousandths between the hub and the outer race of one of the bearings; a few thousandths is ok, but if they aren't tight in the hub they can shift and chafe during use.
Have I overclarified that to mud now?