Synchronizer Ring

Check if the clutch gear teeth are damaged or broken.
Check internal surface for damage, wear and broken threads.

Fig 1: Checking Synchronizer Ring
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
Force the synchronizer ring toward the clutch gear and check clearance "A." If "A" is less than the limit, replace the synchronizer ring.
Minimum limit: 0.5 mm (0.020 inch)

Fig 2: Checking Clearance To Synchronizer Ring
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.