That shim canted the starter away on an angle? Something is not right. It should only take a couple of shims to get the right contact. How about the drive gear? If you pry it out does it snap back in? If so it is OK. I had a similar problem but the stater was an aftermarket high torque unit. It NEVER fit right even though is was spec'd for a Pontiac 400. We ended up getting a new one which worked fine. We never did figure out why the bad one did not fit. Did you pry out the drive gear and test the gears for .020"?
