Good questions Chuck.
I have also heard that cad plating is the correct finish.
The copper bushing spot welded into the bottom (which is news to me) is what the armature sets in - right? I am not sure how to address this issue.
I did just read in the service manual that the “....end case and field assembly is serviced as a unit.” I hope that doesn’t mean it is connected together in some challenging way.
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Sam... 
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