Quote - "All parts are using the same smoothing of 22.5 and it is rendered with smoothing off."

Do you mean crease angle? That's kind of low - might be the problem. Try increasing that.

Yes. I meant crease angle.  I raised it and got the same result. 
This is confusing me because back in November I rendered using the same maps and models, and didn't have the banding.  I don't know what has changed.