TM10-3930-660-34 4-6. TURBOCHARGER ASSEMBLY - REPAIR (Cont’d) 19.  REMOVE TWO OUTER RETAINING RINGS (27) FROM BORE OF BEARING HOUSING (2).  DISCARD RETAINING RINGS (27). 20.  REMOVE TWO BEARINGS (28).  DISCARD BEARINGS (28). 21.  REMOVE TWO INNER RETAINING RINGS (29) FROM BORE OF BEARING HOUSING (2).  DISCARD RETAINING RINGS (29). CLEANING CAUTION Do not use a wire brush on the compressor wheel.  Use of a wire brush on compressor wheel may cause premature component failure. 1.   USE A SCRAPER AND MEDIUM GRIT EMERY CLOTH TO REMOVE CARBON BUILDUP FROM TURBINE HOUSING (3). 2.   POLISH BEARING SURFACES ON SHAFT (24) WITH CROCUS CLOTH. 3.   FOR GENERAL CLEANING INSTRUCTIONS, SEE CLEANING INSTRUCTIONS,  PARA. 2-10. INSPECTION 1.   MEASURE SHAFT (24) BEARING DIAMETER. SHAFT BEARING SURFACE MINIMUM DIAMETER IS 0.432 INCH. 2.   FOR GENERAL INSPECTION INSTRUCTIONS, SEE INSPECTION INSTRUCTIONS,  PARA. 2-11. ASSEMBLY NOTE Balance marks on shaft (24),  thrust collar (20) and impeller (10) must be aligned to make sure rotating parts of turbocharger are properly balanced. 1.   APPLY ENGINE OIL TO GROOVE (B) ON SHAFT (24). 4-18