Check that the linkage is not the problem first.
If linkage is ok them remove the trans axle which is held to the chassis with 4 M8 bolts. Remove the drive belt and the 2 split pins from the gear change link and the clutch link.
With the box on a bench with the drive pulley on top remove the two grubscrews which are the gear selector indent screws. There is a spring and a ball bearing under each screw,remove them. Now remove all the bolts from the top of the box. Now the top half of the box will lift off.
In top half of the box check the movement of the gear selector arm .If it is tight ,remove it and clean grease and refit. Check that the selector plate is not bent,it can be flattened if necessary.
In the lower half of the box there is a collar with a grove that the selector engages with. It is this collar that moves during gearchanges as it has sprung keys attached that lock into the gear selected. Check that the collar moves ok and clicks into each gear. If all is well refit cover and finally the ball bearings springs and grub screwa
Dave Francis, April 2010
