Cut out some small wedges of paper (with an angle of 20-30°) and fold them in half lengthwise to double the thickness. Firmly but very carefully insert one into the bearing between two of the balls, next to the outer race. Rotate the bearing several turns, then remove the paper. There’s probably some black gunk on the paper. Do it again with a clean piece. Also insert pieces next to the inner race to scrub that as well. Repeat this until you stop getting gunk on the paper. At this point your bearing should be bone dry and very clean. If you want, you can dip a wedge in oil and touch one of the races a few times to lube it up.
I also do this right after I clean my bearings with mineral spirits, before they dry. The paper directly absorbs the liquid and helps prevent residue from building up. As long as I’ve been doing this, I’ve never locked up a bearing. In fact, I’ve rescued several ‘dead’ bearings with this method as well.