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

Water Pump Impeller Disassembly/Assembly
Water Pump Housing DisassemblySeat Cover Installation
Installation is the reverse of removal. Note the following.
When installing the pad [A], install it along the corner [B]
as shown in the figure.
When installing the pad [C], align the ends [D], along the
corner [E], and wrap [F] the upper edge of the seat cover.
Install the damper [A] ...
Stick Coil Removal
Remove the air cleaner housing (see Air Cleaner Housing
Removal in the Fuel System (DFI) chapter).
Disconnect the stick coil connectors [A].
Pull out the stick coils [B] upward.
First, turn the stick coil by 90 degrees, and then pull it out
by twisting the coil head to the left and righ ...
Check 3-6: Neutral Indicator Light (LED) Inspection
Connect the leads in the same circuit as Check 3-2.
Connect the terminal [8] to the battery (–) terminal.
Check that the neutral indicator light (LED) [A] goes on.
If the indicator light does not go on, replace the meter unit.
...