You will need: a 10 mm spanner, a screwdriver, a hammer, and a punch
Remove the gear selector mechanism (see "Repairing the VAZ-2123 gearbox")
Remove the clamp from the mechanism rod.
Remove the mechanism rod cover.
Knock out the pivot pin of the traction rod.
Remove the pivot from the gear selector lever.
Remove the hinge axis.
Remove the bushings traction eyes.
Replace them if necessary.
Remove the protective cover of the mechanism housing and the spring.
Remove the retaining and sealing rings.
Replace the rings if necessary.
Remove the spherical washer.
Unscrew the three nuts securing the gear selector lever flange.
Remove the flange, seal and two lever gaskets.
Remove the guide plate washer.
Remove the springs and lever from the guide plate
Assemble the gear selection mechanism in the reverse order of removal.
Disassembling and assembling the gear selection mechanism drive
You will need: keys "10", "13", screwdriver.
Remove the gear selector drive (see "How to replace the Niva Chevrolet gearbox").
Unscrew the two nuts securing the bracket to the support plate.
Remove the bushings from the plate holes.
Do not lose them during assembly.
Remove the protective covers.
Remove the four bolts securing the lever housing to the support plate.
Remove the upper part of the lever housing.
Unscrew the two bolts securing the reverse lock pad to the lever housing and remove the pad.
Use pliers to remove the retaining ring and remove the ball joint of the lever from the ball joint housing.
Remove the seal from the ball joint and inspect it. Replace the sealing rings if necessary.
Remove the gear shift lever axle nut.
Remove the axle and disconnect the lever.
Unscrew the locking stop mounting screw and remove it.
Unscrew the three nuts securing the ball joint housing and remove it.
Remove the spring. Inspect it and replace it if necessary.
Assemble the gear selector mechanism drive in the reverse order of removal.
For disassembling and adjusting the gear shift mechanism, see this article - Removing and adjusting the gear shift mechanism Niva Chevrolet since 2009.