Synchronizer Ring

Check the clutch gear teeth for damage and broken.
Check internal surface for damage, wear and broken threads.

Fig 1: Checking Clutch Gear Teeth For Damage And Broken
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.
1. Minimum limit: 0.5 mm (0.020 inch)
Fig 2: Forcing Synchronizer Ring Toward Clutch Gear
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.