TM10-3930-660-34 16-21.PISTON PUMP - REPAIR (Cont’d) d.  Use tapered feeler gauge to measure opening between valve block (3) and housing (6).Four measurements should be obtained equidistant around unit.  Average four readings by adding them together and dividing by 4. Calculate thickness of shaft bearing spacer as shown in the following example: + 0.150 in.  = Measured thickness of bearing spacer - 0.027 in.  = Average gap (estimated) + 0.003 + 0.001 in.  = Preload setting + 0.020 in.  = Compressed thickness of gasket 0.146 + 0.001 in.  = Required bearing spacer thickness to provide a 0.003 + 0.001 in. bearing preload e.  Remove the six mounting screws (8),  then remove housing (6) from valve block (3). f.  Remove bearing (13) and thickest bearing spacer (14) from shaft (15). g.  Locate bearing spacer (14) in kit with dimensions calculated in step d above.  Place spacer (14) next to the new bearing (13) on shaft (15),  with chamfer of spacer facing the shaft shoulder. Use the original spacer (14) and bearing (13) if preload is not required.  Set aside until final assembly is performed. 16-139