Went to install my starter today got it in fine and all, went to fire it up and it did just fine but its knockin really bad. Turns out its not gripin on the flywheel correctly. Went back to autozone and the general mannager said i needed to shim it. I for the heck of my life cant get the shimms in to try it. My father says i dont need to do it, I've never had to do it the past 14 years have done it. The starter's teeth at the end is sheering off and had metal shavings in it after i pulled it out, I only ran it for about 3 seconds. is autozone nuts or is my father? If i need to shimm it how do i get the freakin shimms to stay on?