at whits end

[1tonchevy]

im at whits end with this starter installed it no shims like my last starter worked awsome 4 days later starter has slight grind :S so i get a shim kit install 2 shims as per my old boss (great mechanic) tryed starting it started with a slight grind. turned it off started it again huge grind. > so i try three shims starts awsome tred a few more times starts awsome then last try GRIND! what am i doing wrong?