Degrease ball bearing around the circumference (outer diameter) with a cloth moistened with ethyl alcohol. Then put the bearing aside. To prevent injury when dealing with superglue, wear safety glasses and thin gloves. Keep the adhesive out of reach of children. Dispose of the adhesive after use so that your children are safe! (There are also commercially available ball bearing adhesives available, such as Loctite). Dip a toothpick into the superglue (several times until the surface of the toothpick absorbs and binds with the glue and absorbs the excess on the surface). Insert the toothpick in the hole so that the adhesive can be applied thinly. If a drop (too much) forms, use a cloth to (touch) carefully "absorb" it.