Remove the transmission shafts (see this chapter).
Using the circlip pliers (special tool), remove the circlips,
and disassemble the transmission shaft.
Special Tool - Outside Circlip Pliers: 57001-144
The 4th gear [A] on the output shaft has three steel balls for
the positive neutral finder mechanism.
Remove the 4th gear as follows.
Set the output shaft in a vertical position holding the 3rd
Spin the 4th gear quickly [C] and pull it off upward.
Refer to the transmission assembly illustration on ahead.
Align each gear oil hole with the drive shaft oil hole when
installing the 3rd gear  and the 5th gear .
Align each oil hole with the output shaft oil hole, when
installing the 3rd gear , bushing , and the 5th gear
Do not apply grease to the steel balls to hold them
in place. This will cause the positive neutral finder
mechanism to malfunction.
Fit the three steel balls [A] into the holes [B] of the output
4th gear [C], and then install the gear on the output shaft
so that the steel balls align with the recesses [D] in the
After assembling the 4th gear with steel balls in place on
the output shaft, check the ball-locking effect that the 4th
gear does not come out of the output shaft when moving
it up and down by hand.
Replace any circlip [A] that were removed with new ones.
Install the circlips so that the opening [B] is aligned with a
spline groove [C].