Carl, FWIW, I have a SHUCKS (New) i.e. Reman unit in the garage I got 20 years ago and never installed because I had my orig rebuilt by ASL (Sparks,Nev) I opened the box and gave her a spin and just as you describe it takes some effort and has a hesitation (drag) at portions of the rotation. I think this is normal. Some thing about carbon vanes rotating in a non-concentric bore acts as the air 'pump'.
Jim