P61 Rotor Bearing Plate Expanding Tool
The tapered head of the retaining screw will center the bearing on the housing. Keep it snug but do not over tighten. While keeping the roller straight with the housing, apply some pressure as the housing spins and it will expand the outer edge.
Then check and see how the fit is commencing (you can use dial calipers or another precision measuring device). You may have to make several attempts so don't try to finish the job all at once. You can "dial in" on the fit and do a great job, so proceed slowly. As always, use with commonly accepted industrial safety procedures.