here is where you can get the Bearing
http://www.drillspot.com/products/462029/Dynaroll_SMR128ZZ_A5_Miniature_Ball_Bearing
http://www.bearingboys.co.uk/MF128-ZZ_Flanged_Shielded_Miniature_Ball_Bearing-62818-p
(hopefully I found the right one at Bearing Boys if not please inform me and Ill fix the link.. Everything is the same except the manufacture and the first 3-2 letters. From SMR to MF )