Use a gauge to measure the clearance between fork pin and the slot on the selector drum.
If the service limit is exceeded, determine which part must be replaced by comparing these dimensions with those of new components (sect. 3 - 1.1, Gearbox).
Also check the wear on the drum support pins; these must not show any signs of scoring, burrs, or deformation.
Turn the drum in the crankcase to establish the extent of radial play. If play is excessive, change whichever part is most worn.


Inspection of the gear selector forks
Reassembly of the gearbox shaftsCrankcase halves
Bearing
Bearing holder bushing
Alternator-side crankcase half
Bearing
Circlip
Washer
Bearing
Sealing ring
Bearing
Retaining plate
Screw
Screw
Clutch-side crankcase half
Sealing ring
Bearing
Circlip
Bearing holder bushing
Bearing
Plug
Screw
Spacer
Bush ...
Disassembly of gear interlock plunger and pawl assembly
Unscrew the interlock plunger screw (5) and remove the seal (6), spring (7)
and the detent ball (8).
Unscrew the clutch-side crankcase half screw (3) and remove the pawl (4),
washer (2) and spring (1).
...
Refitting the gear selector lever
Position the gearbox drum selector fork in the centre of the gear rollers.
Position the gear selector lever (21) together with control shaft, spring and
plate into the chain-side crankcase half.
Insert the screws (18) and (20) with the spacer (19).
Temporarily fit gear change lever (or a ...