I have a 97 zl 440 and had to pull the chain case and drive gears apart last year to put a new track on. After i put it all together i noticed there is a grinding noise inside the case when i slam on the throttle from a stop. I pulled it apart again last week and realized the inside drive sprocket that goes on the shaft first is rubbing against the bolts and nuts of the bearing housing. I put an extra spacer in their and by hand i spun it and it wasnt grinding but when i ran it it did the same old thing. Any suggestions on how to fix this?