John,
I wouldn't try to shim it as it will likely cause other problems.
Did you also replace the fiber plates in your clutch? If so, what type did you use? I've heard that some aftermarket plates can be thicker than stocker and may cause your problem. If you did change the plates and still have your old ones, stick 'em back in to see.
Also check to ensure there is only one washer (92022 below) between the case and basket, and one washer between the basket and inner hub.
Good Luck,
Scott