To measure, you would have to remove the prop drive, so you can set the dial directly next to the bearing.
I would think 0.01mm to be repair limit.
A loose outer ring in the engine housing is damage due to excessively hot running. (abuse).

PS.
That would be radial displacement from neutral. Total radial movement then is 0.02mm.
On the prop tip, that would be about 0.5mm for a single bearingif you apply slight pressure on the rear prop washer to and fro. However, the engine has two bearings, making it more difficult to measure without complete disassembly.