Place the gearbox on the 23 0 050 rotating stand for disassembly.
Drain the oil from the gearbox housing.
Remove the clutch release fork and the clutch release bearing from the guide sleeve of the front gearbox cover.
Remove the front gearbox cover and take out the adjusting rings.
Remove the retaining ring from the input shaft, then remove the adjusting rings.
Press the front bearing of the input shaft out of the gearbox housing.
On vehicles from the 1978 model year, unscrew the plug of the gear selector rod lock, remove the spring and locking sleeve, unscrew the bolt securing the reverse intermediate gear shaft.
Unscrew the nuts, remove the back cover and press its mounting pins into the sockets.
Install a protective sleeve with a diameter of 28 mm and a length of 25 mm onto the end of the primary shaft and separate the gearbox housing and the rear cover using tool 23 1 1000, which, when tightening the clamping bolt, rests on the shaft through the sleeve, moving the rear cover away from the gearbox housing.
Remove the gearbox housing, press out the rear bearing of the input shaft and remove the adjusting rings.
Unscrew the plug of the gear shift fork rod lock from the rear cover, remove the spring and the locking sleeve.
Engage II gear and push the III and IV gear shift fork pin as far as possible so that it fits between the teeth of the synchronizer clutch hub.
On vehicles from model year 1978, having unscrewed the mounting bolt located on the upper part of the rear cover, turn the gear shift drive rod.
Remove the III and IV gear shift fork rod.
Remove the locking sleeve from the end of the gear selector rod and knock the axle off the rod tip.
Having rested the fork for switching III and IV gears against the sliding sleeve of the synchronizer, remove the gear selection rod from the rear cover by turning the rod upward.
On vehicles from model year 1978, unscrew the fastening bolt on the side surface of the rear cover, remove the reverse gear engagement lever. Remove the reverse gear fork rod and remove the locking ball.
Release the sliding sleeve of the synchronizer of III and IV gears and remove the fork of III and IV gears.
Remove the bushing and take out the speedometer drive driven gear shaft.
Remove the retaining ring from the secondary shaft flange.
Install the centering sleeve 23 1 200 on the secondary shaft and lock the secondary shaft flange with the lock 23 1 140.
After unscrewing the nut, remove the secondary shaft flange, using a puller if necessary.
Remove the rear bearing and adjusting rings from the secondary shaft.
Press the secondary shaft bearing out of the rear cover using a Rillex 23 2 060 mandrel, placing a 2 mm thick piece of sheet metal between the 2nd and 3rd gear pinions to avoid damaging the 2nd gear synchronizer. Remove the adjusting rings.
Raise the primary and secondary shafts slightly and remove the intermediate shaft.
Remove the axle together with the reverse gear fork and the reverse gear intermediate gear. Remove the locking balls.
Remove the primary and secondary shafts together with the rod and the fork for shifting the first and second gears. Remove the locking balls.
Remove the reverse light switch and take out the plug located to the right of it.