When you say that most of them are loose to begin with, how loose should they be?  The two on the complete, previously running motors I have were really quite tight - I couldn't move them with my fingers.  The one on the parts motor is wobbly loose and flops all around.  After being a little aggressive with the one I broke last night, that one too is now wobbly loose but still attached to the case due to those super tight Phillips head screws.

I hit them w/PB Blaster and was going to try them again today.  If they don't want to come out I was going to hit them with a little heat.