Preloading bearings in hydraulic motors

I'm in the process of rebuilding a Eaton motor, model 6433. I've been trying to figure how to preload the bearings. Under the bearing cup on the end of the shaft there are 3 shims. My question is how to tell if I have to many or not enough shims?
When I pulled this motor down the bearing was losing the hardening off the rollers. Would this indicate that the bearing was overloaded?
Cheers Tones

Preloading bearings in hydraulic motors