If the surface is corroded or if the blades are damaged, replace the impeller

Water Pump Impeller Disassembly/Assembly
Water Pump Housing DisassemblyTransmission Shaft Assembly
Apply molybdenum disulfide oil solution to the sliding surfaces
of the gears and shafts.
Install the gears and the gear bushings [A] with their holes
[B] aligned.
Replace any circlips removed with new ones.
Install the circlips [A] so that the opening [B] of it is aligned
with ...
Special Tools
Bearing Driver Set:
57001-1129
Jack:
57001-1238
Bearing Remover Head, 25 × 28:
57001-1346
Bearing Remover Shaft, 13:
57001-1377
Jack Attachment:
57001-1608 ...
Balance Adjustment
If the wheel always stops in one position, provisionally
attach a balance weight [A] on the rim at the marking using
adhesive tape.
Rotate the wheel 1/4 turn [B], and see whether or not the
wheel stops in this position. If it does, the correct balance
weight is being used.
If the whe ...