Synchronizer wornout
Gear teeth wornout
Synchronizing unit stuck
In adequate lubrication
Lubricate the unit
Check and realign
Adjust clutch pedal free play
Re - install springs correctly
Bearing worn out or dry
Synchronizer defective
Synchronizer worn-out
Noise in gear shifting
Gear slip
Gear locked in one gear
Gear clash during shifting
Bearing worn out
Synchronizing unit damaged
Fly wheel ring wornout