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

Water Pump Impeller Disassembly/Assembly
Water Pump Housing DisassemblySeparator Operation Test
WARNINGGasoline is extremely flammable and can be
explosive
under certain conditions. Turn the ignition
switch OFF. Do not smoke. Make sure the area is
well-ventilated and free from any source of flame
or sparks; this includes any appliance with a pilot
light.
...
Check 3-3: High Beam Indicator Light (LED) Inspection
Connect the leads in the same circuit as Check 3-2.
Connect the terminal [7] to the battery (+) terminal.
Check that the high beam indicator light (LED) [A] goes
on.
If the indicator light does not go on, replace the meter unit.
...
Evaporative Emission Control System (California
model only)
This system routes fuel vapors from
the fuel system into the running engine
or stores the vapors in a canister when
the engine is stopped. Although no adjustments
are required, a thorough visual
inspection must be made at the intervals
specified by the Periodic Maintenance
Chart.
Inspection
...