The thing you call the insert spring is actually called a coupling ring by nissan. It couples the shaft bound gear onto the needle bearing gear driven the countershaft gear.
I have never heard anyone ever say that the baulk (synchronising) ring ever grinds. What people refer to is the fact that the baulk ring fails to synchronise the speed of the countershaft to the speed of the output shaft quickly enough and the coupling ring grinds against the dog teeth on the gear. As a result of this there is damage done to the teeth on both the coupling ring and the gear dog teeth which can lead to difficult shifting or random grindingeven if the baulk ring has successfully matched the shaft speeds.
