you are right abbasi sab it will take of less meterial but this is the only shift drum i own right now am looking for complete gearbox assembly but no luck till yet . in first pic the bolt is pushing shift drum with steel ball i guess for neutral gear i losen that bolt even taken it off from assembly to check if this part giving problem but no luck
2nd pic is example of shift drum and today i will open the crankcase to find any worn spots on my shift drum
third pic is kind of gear shift mechanism black arrow part is spring which was little curvy i thought it will resolve the problem but no luck
yellow arrow is my shift drum and the red one is gear shifting lever . i detach everything except shift drum and pushed it clock and anti clock wise using screw driver but seem like the problem is inside so tonight i will open the crank case to check thoroughly inside problem