Synchronizer Ring

Check that the outer synchronizer ring clutch gear is free of damage.
Check that the synchronizer rings and synchronizer cones are free of damage or wear in the contact surface and broken screw threads.
Check that the outer synchronizer ring and synchronizer key contact surface is free of damage and wear.

Fig 1: Locating Synchronizer Ring Wear And Damage Area
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
Join the outer and inner synchronizer rings and synchronizer cone together and check clearance "A" shown in the illustration. If "A" is less than the limit value, replace them.
Limit A (from back of outer ring to clutch gear): 0.5 mm (0.02 inch)

Fig 2: Identifying Distance From Back Of Outer Ring To Clutch Gear
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.